Bring our tzcode up to date.

* Replay 2010[acflm] which had been merged but not recorded.
* Merge 2010n.
* Reorganize (unsplit) the code to match the upstream layout.
* Merge 2022[cdefg].

MFC after:      1 week
Sponsored by:   Klara, Inc.

62 files changed, 25079 insertions, 8326 deletions

diff --git a/contrib/tzcode/CONTRIBUTING b/contrib/tzcode/CONTRIBUTING
new file mode 100644
index 000000000000..4c0f56a50265
--- /dev/null
+++ b/contrib/tzcode/CONTRIBUTING
@@ -0,0 +1,97 @@
+# Contributing to the tz code and data
+
+Please do not create issues or pull requests on GitHub, as the
+proper procedure for proposing and distributing patches is via
+email as described below.
+
+The time zone database is by no means authoritative: governments
+change timekeeping rules erratically and sometimes with little
+warning, the data entries do not cover all of civil time before
+1970, and undoubtedly errors remain in the code and data.  Feel
+free to fill gaps or fix mistakes, and please email improvements
+to <tz@iana.org> for use in the future.  In your email, please give
+reliable sources that reviewers can check.
+
+## Contributing technical changes
+
+To email small changes, please run a POSIX shell command like
+'diff -u old/europe new/europe >myfix.patch', and attach
+'myfix.patch' to the email.
+
+For more-elaborate or possibly-controversial changes,
+such as renaming, adding or removing zones, please read
+"Theory and pragmatics of the tz code and data"
+<https://www.iana.org/time-zones/repository/theory.html>.
+It is also good to browse the mailing list archives
+<https://mm.icann.org/pipermail/tz/> for examples of patches that tend
+to work well.  Additions to data should contain commentary citing
+reliable sources as justification.  Citations should use "https:" URLs
+if available.
+
+For changes that fix sensitive security-related bugs, please see the
+distribution's 'SECURITY' file.
+
+Please submit changes against either the latest release
+<https://www.iana.org/time-zones> or the main branch of the development
+repository.  The latter is preferred.
+
+## Sample Git workflow for developing contributions
+
+If you use Git the following workflow may be helpful:
+
+  * Copy the development repository.
+
+        git clone https://github.com/eggert/tz.git
+        cd tz
+
+  * Get current with the main branch.
+
+        git checkout main
+        git pull
+
+  * Switch to a new branch for the changes.  Choose a different
+    branch name for each change set.
+
+        git checkout -b mybranch
+
+  * Sleuth by using 'git blame'.  For example, when fixing data for
+    Africa/Sao_Tome, if the command 'git blame africa' outputs a line
+    '2951fa3b (Paul Eggert 2018-01-08 09:03:13 -0800 1068) Zone
+    Africa/Sao_Tome 0:26:56 - LMT 1884', commit 2951fa3b should
+    provide some justification for the 'Zone Africa/Sao_Tome' line.
+
+  * Edit source files.  Include commentary that justifies the
+    changes by citing reliable sources.
+
+  * Debug the changes, e.g.:
+
+        make check
+        make install
+        ./zdump -v America/Los_Angeles
+
+  * For each separable change, commit it in the new branch, e.g.:
+
+        git add northamerica
+        git commit
+
+    See recent 'git log' output for the commit-message style.
+
+  * Create patch files 0001-..., 0002-..., ...
+
+        git format-patch main
+
+  * After reviewing the patch files, send the patches to <tz@iana.org>
+    for others to review.
+
+        git send-email main
+
+    For an archived example of such an email, see
+    "[PROPOSED] Fix off-by-1 error for Jamaica and T&C before 1913"
+    <https://mm.icann.org/pipermail/tz/2018-February/026122.html>.
+
+  * Start anew by getting current with the main branch again
+    (the second step above).
+
+-----
+
+This file is in the public domain.
diff --git a/contrib/tzcode/LICENSE b/contrib/tzcode/LICENSE
new file mode 100644
index 000000000000..8ba4399c622d
--- /dev/null
+++ b/contrib/tzcode/LICENSE
@@ -0,0 +1,5 @@
+Unless specified below, all files in the tz code and data (including
+this LICENSE file) are in the public domain.
+
+If the files date.c, newstrftime.3, and strftime.c are present, they
+contain material derived from BSD and use the BSD 3-clause license.
diff --git a/contrib/tzcode/Makefile b/contrib/tzcode/Makefile
new file mode 100644
index 000000000000..afb9d538a203
--- /dev/null
+++ b/contrib/tzcode/Makefile
@@ -0,0 +1,1250 @@
+# Make and install tzdb code and data.
+
+# This file is in the public domain, so clarified as of
+# 2009-05-17 by Arthur David Olson.
+
+# Package name for the code distribution.
+PACKAGE=	tzcode
+
+# Version number for the distribution, overridden in the 'tarballs' rule below.
+VERSION=	unknown
+
+# Email address for bug reports.
+BUGEMAIL=	tz@iana.org
+
+# DATAFORM selects the data format.
+# Available formats represent essentially the same data, albeit
+# possibly with minor discrepancies that users are not likely to notice.
+# To get new features and the best data right away, use:
+#	DATAFORM=	vanguard
+# To wait a while before using new features, to give downstream users
+# time to upgrade zic (the default), use:
+#	DATAFORM=	main
+# To wait even longer for new features, use:
+#	DATAFORM=	rearguard
+# Rearguard users might also want "ZFLAGS = -b fat"; see below.
+DATAFORM=		main
+
+# Change the line below for your timezone (after finding the one you want in
+# one of the $(TDATA) source files, or adding it to a source file).
+# Alternatively, if you discover you've got the wrong timezone, you can just
+# 'zic -l -' to remove it, or 'zic -l rightzone' to change it.
+# Use the command
+#	make zonenames
+# to get a list of the values you can use for LOCALTIME.
+
+LOCALTIME=	Factory
+
+# The POSIXRULES macro controls interpretation of nonstandard and obsolete
+# POSIX-like TZ settings like TZ='EET-2EEST' that lack DST transition rules.
+# Such a setting uses the rules in a template file to determine
+# "spring forward" and "fall back" days and times; the environment
+# variable itself specifies UT offsets of standard and daylight saving time.
+#
+# If POSIXRULES is '-', no template is installed; this is the default.
+#
+# Any other value for POSIXRULES is obsolete and should not be relied on, as:
+# * It does not work correctly in popular implementations such as GNU/Linux.
+# * It does not work even in tzcode, except for historical timestamps
+#   that precede the last explicit transition in the POSIXRULES file.
+#   Hence it typically does not work for current and future timestamps.
+# In short, software should avoid ruleless settings like TZ='EET-2EEST'
+# and so should not depend on the value of POSIXRULES.
+#
+# If, despite the above, you want a template for handling these settings,
+# you can change the line below (after finding the timezone you want in the
+# one of the $(TDATA) source files, or adding it to a source file).
+# Alternatively, if you discover you've got the wrong timezone, you can just
+# 'zic -p -' to remove it, or 'zic -p rightzone' to change it.
+# Use the command
+#	make zonenames
+# to get a list of the values you can use for POSIXRULES.
+
+POSIXRULES=	-
+
+# Also see TZDEFRULESTRING below, which takes effect only
+# if the time zone files cannot be accessed.
+
+
+# Installation locations.
+#
+# The defaults are suitable for Debian, except that if REDO is
+# posix_right or right_posix then files that Debian puts under
+# /usr/share/zoneinfo/posix and /usr/share/zoneinfo/right are instead
+# put under /usr/share/zoneinfo-posix and /usr/share/zoneinfo-leaps,
+# respectively.  Problems with the Debian approach are discussed in
+# the commentary for the right_posix rule (below).
+
+# Destination directory, which can be used for staging.
+# 'make DESTDIR=/stage install' installs under /stage (e.g., to
+# /stage/etc/localtime instead of to /etc/localtime).  Files under
+# /stage are not intended to work as-is, but can be copied by hand to
+# the root directory later.  If DESTDIR is empty, 'make install' does
+# not stage, but installs directly into production locations.
+DESTDIR =
+
+# Everything is installed into subdirectories of TOPDIR, and used there.
+# TOPDIR should be empty (meaning the root directory),
+# or a directory name that does not end in "/".
+# TOPDIR should be empty or an absolute name unless you're just testing.
+TOPDIR =
+
+# The default local timezone is taken from the file TZDEFAULT.
+TZDEFAULT = $(TOPDIR)/etc/localtime
+
+# The subdirectory containing installed program and data files, and
+# likewise for installed files that can be shared among architectures.
+# These should be relative file names.
+USRDIR = usr
+USRSHAREDIR = $(USRDIR)/share
+
+# "Compiled" timezone information is placed in the "TZDIR" directory
+# (and subdirectories).
+# TZDIR_BASENAME should not contain "/" and should not be ".", ".." or empty.
+TZDIR_BASENAME=	zoneinfo
+TZDIR = $(TOPDIR)/$(USRSHAREDIR)/$(TZDIR_BASENAME)
+
+# The "tzselect" and (if you do "make INSTALL") "date" commands go in:
+BINDIR = $(TOPDIR)/$(USRDIR)/bin
+
+# The "zdump" command goes in:
+ZDUMPDIR = $(BINDIR)
+
+# The "zic" command goes in:
+ZICDIR = $(TOPDIR)/$(USRDIR)/sbin
+
+# Manual pages go in subdirectories of. . .
+MANDIR = $(TOPDIR)/$(USRSHAREDIR)/man
+
+# Library functions are put in an archive in LIBDIR.
+LIBDIR = $(TOPDIR)/$(USRDIR)/lib
+
+
+# Types to try, as an alternative to time_t.
+TIME_T_ALTERNATIVES = $(TIME_T_ALTERNATIVES_HEAD) $(TIME_T_ALTERNATIVES_TAIL)
+TIME_T_ALTERNATIVES_HEAD = int_least64_t
+TIME_T_ALTERNATIVES_TAIL = int_least32_t uint_least32_t uint_least64_t
+
+# What kind of TZif data files to generate.  (TZif is the binary time
+# zone data format that zic generates; see Internet RFC 8536.)
+# If you want only POSIX time, with time values interpreted as
+# seconds since the epoch (not counting leap seconds), use
+#	REDO=		posix_only
+# below.  If you want only "right" time, with values interpreted
+# as seconds since the epoch (counting leap seconds), use
+#	REDO=		right_only
+# below.  If you want both sets of data available, with leap seconds not
+# counted normally, use
+#	REDO=		posix_right
+# below.  If you want both sets of data available, with leap seconds counted
+# normally, use
+#	REDO=		right_posix
+# below.  POSIX mandates that leap seconds not be counted; for compatibility
+# with it, use "posix_only" or "posix_right".  Use POSIX time on systems with
+# leap smearing; this can work better than unsmeared "right" time with
+# applications that are not leap second aware, and is closer to unsmeared
+# "right" time than unsmeared POSIX time is (e.g., 0.5 vs 1.0 s max error).
+
+REDO=		posix_right
+
+# Whether to put an "Expires" line in the leapseconds file.
+# Use EXPIRES_LINE=1 to put the line in, 0 to omit it.
+# The EXPIRES_LINE value matters only if REDO's value contains "right".
+# If you change EXPIRES_LINE, remove the leapseconds file before running "make".
+# zic's support for the Expires line was introduced in tzdb 2020a,
+# and was modified in tzdb 2021b to generate version 4 TZif files.
+# EXPIRES_LINE defaults to 0 for now so that the leapseconds file
+# can be given to pre-2020a zic implementations and so that TZif files
+# built by newer zic implementations can be read by pre-2021b libraries.
+EXPIRES_LINE=	0
+
+# To install data in text form that has all the information of the TZif data,
+# (optionally incorporating leap second information), use
+#	TZDATA_TEXT=	tzdata.zi leapseconds
+# To install text data without leap second information (e.g., because
+# REDO='posix_only'), use
+#	TZDATA_TEXT=	tzdata.zi
+# To avoid installing text data, use
+#	TZDATA_TEXT=
+
+TZDATA_TEXT=	leapseconds tzdata.zi
+
+# For backward-compatibility links for old zone names, use
+#	BACKWARD=	backward
+# To omit these links, use
+#	BACKWARD=
+
+BACKWARD=	backward
+
+# If you want out-of-scope and often-wrong data from the file 'backzone',
+# but only for entries listed in the backward-compatibility file zone.tab, use
+#	PACKRATDATA=	backzone
+#	PACKRATLIST=	zone.tab
+# If you want all the 'backzone' data, use
+#	PACKRATDATA=	backzone
+#	PACKRATLIST=
+# To omit this data, use
+#	PACKRATDATA=
+#	PACKRATLIST=
+
+PACKRATDATA=
+PACKRATLIST=
+
+# The name of a locale using the UTF-8 encoding, used during self-tests.
+# The tests are skipped if the name does not appear to work on this system.
+
+UTF8_LOCALE=	en_US.utf8
+
+# Non-default libraries needed to link.
+# On some hosts, this should have -lintl unless CFLAGS has -DHAVE_GETTEXT=0.
+LDLIBS=
+
+# Add the following to the end of the "CFLAGS=" line as needed to override
+# defaults specified in the source code.  "-DFOO" is equivalent to "-DFOO=1".
+#  -DDEPRECATE_TWO_DIGIT_YEARS for optional runtime warnings about strftime
+#	formats that generate only the last two digits of year numbers
+#  -DEPOCH_LOCAL if the 'time' function returns local time not UT
+#  -DEPOCH_OFFSET=N if the 'time' function returns a value N greater
+#	than what POSIX specifies, assuming local time is UT.
+#	For example, N is 252460800 on AmigaOS.
+#  -DHAVE_DECL_ASCTIME_R=0 if <time.h> does not declare asctime_r
+#  -DHAVE_DECL_ENVIRON if <unistd.h> declares 'environ'
+#  -DHAVE_DECL_TIMEGM=0 if <time.h> does not declare timegm
+#  -DHAVE_DIRECT_H if mkdir needs <direct.h> (MS-Windows)
+#  -DHAVE_GENERIC=0 if _Generic does not work*
+#  -DHAVE_GETRANDOM if getrandom works (e.g., GNU/Linux),
+#	-DHAVE_GETRANDOM=0 to avoid using getrandom
+#  -DHAVE_GETTEXT if gettext works (e.g., GNU/Linux, FreeBSD, Solaris),
+#	where LDLIBS also needs to contain -lintl on some hosts;
+#	-DHAVE_GETTEXT=0 to avoid using gettext
+#  -DHAVE_INCOMPATIBLE_CTIME_R if your system's time.h declares
+#	ctime_r and asctime_r incompatibly with the POSIX standard
+#	(Solaris when _POSIX_PTHREAD_SEMANTICS is not defined).
+#  -DHAVE_INTTYPES_H=0 if <inttypes.h> does not work*
+#  -DHAVE_LINK=0 if your system lacks a link function
+#  -DHAVE_LOCALTIME_R=0 if your system lacks a localtime_r function
+#  -DHAVE_LOCALTIME_RZ=0 if you do not want zdump to use localtime_rz
+#	localtime_rz can make zdump significantly faster, but is nonstandard.
+#  -DHAVE_MALLOC_ERRNO=0 if malloc etc. do not set errno on failure.
+#  -DHAVE_POSIX_DECLS=0 if your system's include files do not declare
+#	functions like 'link' or variables like 'tzname' required by POSIX
+#  -DHAVE_SETENV=0 if your system lacks the setenv function
+#  -DHAVE_SNPRINTF=0 if your system lacks the snprintf function
+#  -DHAVE_STDCKDINT_H=0 if neither <stdckdint.h> nor substitutes like
+#	__builtin_add_overflow work*
+#  -DHAVE_STDINT_H=0 if <stdint.h> does not work*
+#  -DHAVE_STRFTIME_L if <time.h> declares locale_t and strftime_l
+#  -DHAVE_STRDUP=0 if your system lacks the strdup function
+#  -DHAVE_STRTOLL=0 if your system lacks the strtoll function
+#  -DHAVE_SYMLINK=0 if your system lacks the symlink function
+#  -DHAVE_SYS_STAT_H=0 if <sys/stat.h> does not work*
+#  -DHAVE_TZSET=0 if your system lacks a tzset function
+#  -DHAVE_UNISTD_H=0 if <unistd.h> does not work*
+#  -DHAVE_UTMPX_H=0 if <utmpx.h> does not work*
+#  -Dlocale_t=XXX if your system uses XXX instead of locale_t
+#  -DRESERVE_STD_EXT_IDS if your platform reserves standard identifiers
+#	with external linkage, e.g., applications cannot define 'localtime'.
+#  -Dssize_t=long on hosts like MS-Windows that lack ssize_t
+#  -DSUPPRESS_TZDIR to not prepend TZDIR to file names; this has
+#	security implications and is not recommended for general use
+#  -DTHREAD_SAFE to make localtime.c thread-safe, as POSIX requires;
+#	not needed by the main-program tz code, which is single-threaded.
+#	Append other compiler flags as needed, e.g., -pthread on GNU/Linux.
+#  -Dtime_tz=\"T\" to use T as the time_t type, rather than the system time_t
+#	This is intended for internal use only; it mangles external names.
+#  -DTZ_DOMAIN=\"foo\" to use "foo" for gettext domain name; default is "tz"
+#  -DTZ_DOMAINDIR=\"/path\" to use "/path" for gettext directory;
+#	the default is system-supplied, typically "/usr/lib/locale"
+#  -DTZDEFRULESTRING=\",date/time,date/time\" to default to the specified
+#	DST transitions if the time zone files cannot be accessed
+#  -DUNINIT_TRAP if reading uninitialized storage can cause problems
+#	other than simply getting garbage data
+#  -DUSE_LTZ=0 to build zdump with the system time zone library
+#	Also set TZDOBJS=zdump.o and CHECK_TIME_T_ALTERNATIVES= below.
+#  -DZIC_BLOAT_DEFAULT=\"fat\" to default zic's -b option to "fat", and
+#	similarly for "slim".  Fat TZif files work around incompatibilities
+#	and bugs in some TZif readers, notably older ones that
+#	ignore or otherwise mishandle 64-bit data in TZif files;
+#	however, fat TZif files may trigger bugs in newer TZif readers.
+#	Slim TZif files are more efficient, and are the default.
+#  -DZIC_MAX_ABBR_LEN_WO_WARN=3
+#	(or some other number) to set the maximum time zone abbreviation length
+#	that zic will accept without a warning (the default is 6)
+#  $(GCC_DEBUG_FLAGS) if you are using recent GCC and want lots of checking
+#
+# * Options marked "*" can be omitted if your compiler is C23 compatible.
+#
+# Select instrumentation via "make GCC_INSTRUMENT='whatever'".
+GCC_INSTRUMENT = \
+  -fsanitize=undefined -fsanitize-address-use-after-scope \
+  -fsanitize-undefined-trap-on-error -fstack-protector
+# Omit -fanalyzer from GCC_DEBUG_FLAGS, as it makes GCC too slow.
+GCC_DEBUG_FLAGS = -DGCC_LINT -g3 -O3 -fno-common \
+  $(GCC_INSTRUMENT) \
+  -Wall -Wextra \
+  -Walloc-size-larger-than=100000 -Warray-bounds=2 \
+  -Wbad-function-cast -Wbidi-chars=any,ucn -Wcast-align=strict -Wdate-time \
+  -Wdeclaration-after-statement -Wdouble-promotion \
+  -Wduplicated-branches -Wduplicated-cond \
+  -Wformat=2 -Wformat-overflow=2 -Wformat-signedness -Wformat-truncation \
+  -Wimplicit-fallthrough=5 -Winit-self -Wlogical-op \
+  -Wmissing-declarations -Wmissing-prototypes -Wnested-externs \
+  -Wnull-dereference \
+  -Wold-style-definition -Woverlength-strings -Wpointer-arith \
+  -Wshadow -Wshift-overflow=2 -Wstrict-overflow \
+  -Wstrict-prototypes -Wstringop-overflow=4 \
+  -Wstringop-truncation -Wsuggest-attribute=cold \
+  -Wsuggest-attribute=const -Wsuggest-attribute=format \
+  -Wsuggest-attribute=malloc \
+  -Wsuggest-attribute=noreturn -Wsuggest-attribute=pure \
+  -Wtrampolines -Wundef -Wuninitialized -Wunused-macros -Wuse-after-free=3 \
+  -Wvariadic-macros -Wvla -Wwrite-strings \
+  -Wno-address -Wno-format-nonliteral -Wno-sign-compare \
+  -Wno-type-limits
+#
+# If your system has a "GMT offset" field in its "struct tm"s
+# (or if you decide to add such a field in your system's "time.h" file),
+# add the name to a define such as
+#	-DTM_GMTOFF=tm_gmtoff
+# to the end of the "CFLAGS=" line.  If not defined, the code attempts to
+# guess TM_GMTOFF from other macros; define NO_TM_GMTOFF to suppress this.
+# Similarly, if your system has a "zone abbreviation" field, define
+#	-DTM_ZONE=tm_zone
+# and define NO_TM_ZONE to suppress any guessing.  Although these two fields
+# not required by POSIX, a future version of POSIX is planned to require them
+# and they are widely available on GNU/Linux and BSD systems.
+#
+# The next batch of options control support for external variables
+# exported by tzcode.  In practice these variables are less useful
+# than TM_GMTOFF and TM_ZONE.  However, most of them are standardized.
+# #
+# # To omit or support the external variable "tzname", add one of:
+# #	-DHAVE_TZNAME=0 # do not support "tzname"
+# #	-DHAVE_TZNAME=1 # support "tzname", which is defined by system library
+# #	-DHAVE_TZNAME=2 # support and define "tzname"
+# # to the "CFLAGS=" line.  "tzname" is required by POSIX 1988 and later.
+# # If not defined, the code attempts to guess HAVE_TZNAME from other macros.
+# # Warning: unless time_tz is also defined, HAVE_TZNAME=1 can cause
+# # crashes when combined with some platforms' standard libraries,
+# # presumably due to memory allocation issues.
+# #
+# # To omit or support the external variables "timezone" and "daylight", add
+# #	-DUSG_COMPAT=0 # do not support
+# #	-DUSG_COMPAT=1 # support, and variables are defined by system library
+# #	-DUSG_COMPAT=2 # support and define variables
+# # to the "CFLAGS=" line; "timezone" and "daylight" are inspired by
+# # Unix Systems Group code and are required by POSIX 2008 (with XSI) and later.
+# # If not defined, the code attempts to guess USG_COMPAT from other macros.
+# #
+# # To support the external variable "altzone", add
+# #	-DALTZONE=0 # do not support
+# #	-DALTZONE=1 # support "altzone", which is defined by system library
+# #	-DALTZONE=2 # support and define "altzone"
+# # to the end of the "CFLAGS=" line; although "altzone" appeared in
+# # System V Release 3.1 it has not been standardized.
+# # If not defined, the code attempts to guess ALTZONE from other macros.
+#
+# If you want functions that were inspired by early versions of X3J11's work,
+# add
+#	-DSTD_INSPIRED
+# to the end of the "CFLAGS=" line.  This arranges for the following
+# functions to be added to the time conversion library.
+# "offtime" is like "gmtime" except that it accepts a second (long) argument
+# that gives an offset to add to the time_t when converting it.
+# "timelocal" is equivalent to "mktime".
+# "timeoff" is like "timegm" except that it accepts a second (long) argument
+# that gives an offset to use when converting to a time_t.
+# "posix2time" and "time2posix" are described in an included manual page.
+# X3J11's work does not describe any of these functions.
+# These functions may well disappear in future releases of the time
+# conversion package.
+#
+# If you don't want functions that were inspired by NetBSD, add
+#	-DNETBSD_INSPIRED=0
+# to the end of the "CFLAGS=" line.  Otherwise, the functions
+# "localtime_rz", "mktime_z", "tzalloc", and "tzfree" are added to the
+# time library, and if STD_INSPIRED is also defined the functions
+# "posix2time_z" and "time2posix_z" are added as well.
+# The functions ending in "_z" (or "_rz") are like their unsuffixed
+# (or suffixed-by-"_r") counterparts, except with an extra first
+# argument of opaque type timezone_t that specifies the timezone.
+# "tzalloc" allocates a timezone_t value, and "tzfree" frees it.
+#
+# If you want to allocate state structures in localtime, add
+#	-DALL_STATE
+# to the end of the "CFLAGS=" line.  Storage is obtained by calling malloc.
+#
+# NIST-PCTS:151-2, Version 1.4, (1993-12-03) is a test suite put
+# out by the National Institute of Standards and Technology
+# which claims to test C and Posix conformance.  If you want to pass PCTS, add
+#	-DPCTS
+# to the end of the "CFLAGS=" line.
+#
+# If you want strict compliance with XPG4 as of 1994-04-09, add
+#	-DXPG4_1994_04_09
+# to the end of the "CFLAGS=" line.  This causes "strftime" to always return
+# 53 as a week number (rather than 52 or 53) for January days before
+# January's first Monday when a "%V" format is used and January 1
+# falls on a Friday, Saturday, or Sunday.
+
+CFLAGS=
+
+# Linker flags.  Default to $(LFLAGS) for backwards compatibility
+# to release 2012h and earlier.
+
+LDFLAGS=	$(LFLAGS)
+
+# For leap seconds, this Makefile uses LEAPSECONDS='-L leapseconds' in
+# submake command lines.  The default is no leap seconds.
+
+LEAPSECONDS=
+
+# The zic command and its arguments.
+
+zic=		./zic
+ZIC=		$(zic) $(ZFLAGS)
+
+# To shrink the size of installed TZif files,
+# append "-r @N" to omit data before N-seconds-after-the-Epoch.
+# To grow the files and work around bugs in older applications,
+# possibly at the expense of introducing bugs in newer ones,
+# append "-b fat"; see ZIC_BLOAT_DEFAULT above.
+# See the zic man page for more about -b and -r.
+ZFLAGS=
+
+# How to use zic to install TZif files.
+
+ZIC_INSTALL=	$(ZIC) -d '$(DESTDIR)$(TZDIR)' $(LEAPSECONDS)
+
+# The name of a Posix-compliant 'awk' on your system.
+# mawk 1.3.3 and Solaris 10 /usr/bin/awk do not work.
+# Also, it is better (though not essential) if 'awk' supports UTF-8,
+# and unfortunately mawk and busybox awk do not support UTF-8.
+# Try AWK=gawk or AWK=nawk if your awk has the abovementioned problems.
+AWK=		awk
+
+# The full path name of a Posix-compliant shell, preferably one that supports
+# the Korn shell's 'select' statement as an extension.
+# These days, Bash is the most popular.
+# It should be OK to set this to /bin/sh, on platforms where /bin/sh
+# lacks 'select' or doesn't completely conform to Posix, but /bin/bash
+# is typically nicer if it works.
+KSHELL=		/bin/bash
+
+# Name of curl <https://curl.haxx.se/>, used for HTML validation.
+CURL=		curl
+
+# Name of GNU Privacy Guard <https://gnupg.org/>, used to sign distributions.
+GPG=		gpg
+
+# This expensive test requires USE_LTZ.
+# To suppress it, define this macro to be empty.
+CHECK_TIME_T_ALTERNATIVES = check_time_t_alternatives
+
+# SAFE_CHAR is a regular expression that matches a safe character.
+# Some parts of this distribution are limited to safe characters;
+# others can use any UTF-8 character.
+# For now, the safe characters are a safe subset of ASCII.
+# The caller must set the shell variable 'sharp' to the character '#',
+# since Makefile macros cannot contain '#'.
+# TAB_CHAR is a single tab character, in single quotes.
+TAB_CHAR=	'	'
+SAFE_CHARSET1=	$(TAB_CHAR)' !\"'$$sharp'$$%&'\''()*+,./0123456789:;<=>?@'
+SAFE_CHARSET2=	'ABCDEFGHIJKLMNOPQRSTUVWXYZ[\\^_`'
+SAFE_CHARSET3=	'abcdefghijklmnopqrstuvwxyz{|}~'
+SAFE_CHARSET=	$(SAFE_CHARSET1)$(SAFE_CHARSET2)$(SAFE_CHARSET3)
+SAFE_CHAR=	'[]'$(SAFE_CHARSET)'-]'
+
+# These characters are Latin-1, and so are likely to be displayable
+# even in editors with limited character sets.
+UNUSUAL_OK_LATIN_1 = «°±»½¾×
+# This IPA symbol is represented in Unicode as the composition of
+# U+0075 and U+032F, and U+032F is not considered alphabetic by some
+# grep implementations that do not grok composition.
+UNUSUAL_OK_IPA = u̯
+# Non-ASCII non-letters that OK_CHAR allows, as these characters are
+# useful in commentary.
+UNUSUAL_OK_CHARSET= $(UNUSUAL_OK_LATIN_1)$(UNUSUAL_OK_IPA)
+
+# Put this in a bracket expression to match spaces.
+s = [:space:]
+
+# OK_CHAR matches any character allowed in the distributed files.
+# This is the same as SAFE_CHAR, except that UNUSUAL_OK_CHARSET and
+# multibyte letters are also allowed so that commentary can contain a
+# few safe symbols and people's names and can quote non-English sources.
+# Other non-letters are limited to ASCII renderings for the
+# convenience of maintainers using XEmacs 21.5.34, which by default
+# mishandles Unicode characters U+0100 and greater.
+OK_CHAR=	'[][:alpha:]$(UNUSUAL_OK_CHARSET)'$(SAFE_CHARSET)'-]'
+
+# SAFE_LINE matches a line of safe characters.
+# SAFE_SHARP_LINE is similar, except any OK character can follow '#';
+# this is so that comments can contain non-ASCII characters.
+# OK_LINE matches a line of OK characters.
+SAFE_LINE=	'^'$(SAFE_CHAR)'*$$'
+SAFE_SHARP_LINE='^'$(SAFE_CHAR)'*('$$sharp$(OK_CHAR)'*)?$$'
+OK_LINE=	'^'$(OK_CHAR)'*$$'
+
+# Flags to give 'tar' when making a distribution.
+# Try to use flags appropriate for GNU tar.
+GNUTARFLAGS= --format=pax --pax-option='delete=atime,delete=ctime' \
+  --numeric-owner --owner=0 --group=0 \
+  --mode=go+u,go-w --sort=name
+TARFLAGS=	`if tar $(GNUTARFLAGS) --version >/dev/null 2>&1; \
+		 then echo $(GNUTARFLAGS); \
+		 else :; \
+		 fi`
+
+# Flags to give 'gzip' when making a distribution.
+GZIPFLAGS=	-9n
+
+# When comparing .tzs files, use GNU diff's -F'^TZ=' option if supported.
+# This makes it easier to see which Zone has been affected.
+DIFF_TZS=	 diff -u$$(! diff -u -F'^TZ=' - - <>/dev/null >&0 2>&1 \
+			   || echo ' -F^TZ=')
+
+###############################################################################
+
+#MAKE=		make
+
+cc=		cc
+CC=		$(cc) -DTZDIR='"$(TZDIR)"'
+
+AR=		ar
+
+# ':' on typical hosts; 'ranlib' on the ancient hosts that still need ranlib.
+RANLIB=		:
+
+TZCOBJS=	zic.o
+TZDOBJS=	zdump.o localtime.o asctime.o strftime.o
+DATEOBJS=	date.o localtime.o strftime.o asctime.o
+LIBSRCS=	localtime.c asctime.c difftime.c strftime.c
+LIBOBJS=	localtime.o asctime.o difftime.o strftime.o
+HEADERS=	tzfile.h private.h
+NONLIBSRCS=	zic.c zdump.c
+NEWUCBSRCS=	date.c
+SOURCES=	$(HEADERS) $(LIBSRCS) $(NONLIBSRCS) $(NEWUCBSRCS) \
+			tzselect.ksh workman.sh
+MANS=		newctime.3 newstrftime.3 newtzset.3 time2posix.3 \
+			tzfile.5 tzselect.8 zic.8 zdump.8
+MANTXTS=	newctime.3.txt newstrftime.3.txt newtzset.3.txt \
+			time2posix.3.txt \
+			tzfile.5.txt tzselect.8.txt zic.8.txt zdump.8.txt \
+			date.1.txt
+COMMON=		calendars CONTRIBUTING LICENSE Makefile \
+			NEWS README SECURITY theory.html version
+WEB_PAGES=	tz-art.html tz-how-to.html tz-link.html
+CHECK_WEB_PAGES=check_theory.html check_tz-art.html \
+			check_tz-how-to.html check_tz-link.html
+DOCS=		$(MANS) date.1 $(MANTXTS) $(WEB_PAGES)
+PRIMARY_YDATA=	africa antarctica asia australasia \
+		europe northamerica southamerica
+YDATA=		$(PRIMARY_YDATA) etcetera
+NDATA=		factory
+TDATA_TO_CHECK=	$(YDATA) $(NDATA) backward
+TDATA=		$(YDATA) $(NDATA) $(BACKWARD)
+ZONETABLES=	zone1970.tab zone.tab
+TABDATA=	iso3166.tab $(TZDATA_TEXT) $(ZONETABLES)
+LEAP_DEPS=	leapseconds.awk leap-seconds.list
+TZDATA_ZI_DEPS=	ziguard.awk zishrink.awk version $(TDATA) \
+		  $(PACKRATDATA) $(PACKRATLIST)
+DSTDATA_ZI_DEPS= ziguard.awk $(TDATA) $(PACKRATDATA) $(PACKRATLIST)
+DATA=		$(TDATA_TO_CHECK) backzone iso3166.tab leap-seconds.list \
+			leapseconds $(ZONETABLES)
+AWK_SCRIPTS=	checklinks.awk checktab.awk leapseconds.awk \
+			ziguard.awk zishrink.awk
+MISC=		$(AWK_SCRIPTS)
+TZS_YEAR=	2050
+TZS_CUTOFF_FLAG=	-c $(TZS_YEAR)
+TZS=		to$(TZS_YEAR).tzs
+TZS_NEW=	to$(TZS_YEAR)new.tzs
+TZS_DEPS=	$(YDATA) asctime.c localtime.c \
+			private.h tzfile.h zdump.c zic.c
+TZDATA_DIST = $(COMMON) $(DATA) $(MISC)
+# EIGHT_YARDS is just a yard short of the whole ENCHILADA.
+EIGHT_YARDS = $(TZDATA_DIST) $(DOCS) $(SOURCES) tzdata.zi
+ENCHILADA = $(EIGHT_YARDS) $(TZS)
+
+# Consult these files when deciding whether to rebuild the 'version' file.
+# This list is not the same as the output of 'git ls-files', since
+# .gitignore is not distributed.
+VERSION_DEPS= \
+		calendars CONTRIBUTING LICENSE Makefile NEWS README SECURITY \
+		africa antarctica asctime.c asia australasia \
+		backward backzone \
+		checklinks.awk checktab.awk \
+		date.1 date.c difftime.c \
+		etcetera europe factory iso3166.tab \
+		leap-seconds.list leapseconds.awk localtime.c \
+		newctime.3 newstrftime.3 newtzset.3 northamerica \
+		private.h southamerica strftime.c theory.html \
+		time2posix.3 tz-art.html tz-how-to.html tz-link.html \
+		tzfile.5 tzfile.h tzselect.8 tzselect.ksh \
+		workman.sh zdump.8 zdump.c zic.8 zic.c \
+		ziguard.awk zishrink.awk \
+		zone.tab zone1970.tab
+
+# And for the benefit of csh users on systems that assume the user
+# shell should be used to handle commands in Makefiles. . .
+
+SHELL=		/bin/sh
+
+all:		tzselect zic zdump libtz.a $(TABDATA) \
+		  vanguard.zi main.zi rearguard.zi
+
+ALL:		all date $(ENCHILADA)
+
+install:	all $(DATA) $(REDO) $(MANS)
+		mkdir -p '$(DESTDIR)$(BINDIR)' \
+			'$(DESTDIR)$(ZDUMPDIR)' '$(DESTDIR)$(ZICDIR)' \
+			'$(DESTDIR)$(LIBDIR)' \
+			'$(DESTDIR)$(MANDIR)/man3' '$(DESTDIR)$(MANDIR)/man5' \
+			'$(DESTDIR)$(MANDIR)/man8'
+		$(ZIC_INSTALL) -l $(LOCALTIME) \
+			`case '$(POSIXRULES)' in ?*) echo '-p';; esac \
+			` $(POSIXRULES) \
+			-t '$(DESTDIR)$(TZDEFAULT)'
+		cp -f $(TABDATA) '$(DESTDIR)$(TZDIR)/.'
+		cp tzselect '$(DESTDIR)$(BINDIR)/.'
+		cp zdump '$(DESTDIR)$(ZDUMPDIR)/.'
+		cp zic '$(DESTDIR)$(ZICDIR)/.'
+		cp libtz.a '$(DESTDIR)$(LIBDIR)/.'
+		$(RANLIB) '$(DESTDIR)$(LIBDIR)/libtz.a'
+		cp -f newctime.3 newtzset.3 '$(DESTDIR)$(MANDIR)/man3/.'
+		cp -f tzfile.5 '$(DESTDIR)$(MANDIR)/man5/.'
+		cp -f tzselect.8 zdump.8 zic.8 '$(DESTDIR)$(MANDIR)/man8/.'
+
+INSTALL:	ALL install date.1
+		mkdir -p '$(DESTDIR)$(BINDIR)' '$(DESTDIR)$(MANDIR)/man1'
+		cp date '$(DESTDIR)$(BINDIR)/.'
+		cp -f date.1 '$(DESTDIR)$(MANDIR)/man1/.'
+
+# Calculate version number from git, if available.
+# Otherwise, use $(VERSION) unless it is "unknown" and there is already
+# a 'version' file, in which case reuse the existing 'version' contents
+# and append "-dirty" if the contents do not already end in "-dirty".
+version:	$(VERSION_DEPS)
+		{ (type git) >/dev/null 2>&1 && \
+		  V=`git describe --match '[0-9][0-9][0-9][0-9][a-z]*' \
+				--abbrev=7 --dirty` || \
+		  if test '$(VERSION)' = unknown && V=`cat $@`; then \
+		    case $$V in *-dirty);; *) V=$$V-dirty;; esac; \
+		  else \
+		    V='$(VERSION)'; \
+		  fi; } && \
+		printf '%s\n' "$$V" >$@.out
+		mv $@.out $@
+
+# These files can be tailored by setting BACKWARD, PACKRATDATA, PACKRATLIST.
+vanguard.zi main.zi rearguard.zi: $(DSTDATA_ZI_DEPS)
+		$(AWK) \
+		  -v DATAFORM=`expr $@ : '\(.*\).zi'` \
+		  -v PACKRATDATA='$(PACKRATDATA)' \
+		  -v PACKRATLIST='$(PACKRATLIST)' \
+		  -f ziguard.awk \
+		  $(TDATA) $(PACKRATDATA) >$@.out
+		mv $@.out $@
+# This file has a version comment that attempts to capture any tailoring
+# via BACKWARD, DATAFORM, PACKRATDATA, PACKRATLIST, and REDO.
+tzdata.zi:	$(DATAFORM).zi version zishrink.awk
+		version=`sed 1q version` && \
+		  LC_ALL=C $(AWK) \
+		    -v dataform='$(DATAFORM)' \
+		    -v deps='$(DSTDATA_ZI_DEPS) zishrink.awk' \
+		    -v redo='$(REDO)' \
+		    -v version="$$version" \
+		    -f zishrink.awk \
+		    $(DATAFORM).zi >$@.out
+		mv $@.out $@
+
+version.h:	version
+		VERSION=`cat version` && printf '%s\n' \
+		  'static char const PKGVERSION[]="($(PACKAGE)) ";' \
+		  "static char const TZVERSION[]=\"$$VERSION\";" \
+		  'static char const REPORT_BUGS_TO[]="$(BUGEMAIL)";' \
+		  >$@.out
+		mv $@.out $@
+
+zdump:		$(TZDOBJS)
+		$(CC) -o $@ $(CFLAGS) $(LDFLAGS) $(TZDOBJS) $(LDLIBS)
+
+zic:		$(TZCOBJS)
+		$(CC) -o $@ $(CFLAGS) $(LDFLAGS) $(TZCOBJS) $(LDLIBS)
+
+leapseconds:	$(LEAP_DEPS)
+		$(AWK) -v EXPIRES_LINE=$(EXPIRES_LINE) \
+		  -f leapseconds.awk leap-seconds.list >$@.out
+		mv $@.out $@
+
+# Arguments to pass to submakes of install_data.
+# They can be overridden by later submake arguments.
+INSTALLARGS = \
+ BACKWARD='$(BACKWARD)' \
+ DESTDIR='$(DESTDIR)' \
+ LEAPSECONDS='$(LEAPSECONDS)' \
+ PACKRATDATA='$(PACKRATDATA)' \
+ PACKRATLIST='$(PACKRATLIST)' \
+ TZDEFAULT='$(TZDEFAULT)' \
+ TZDIR='$(TZDIR)' \
+ ZIC='$(ZIC)'
+
+INSTALL_DATA_DEPS = zic leapseconds tzdata.zi
+
+# 'make install_data' installs one set of TZif files.
+install_data: $(INSTALL_DATA_DEPS)
+		$(ZIC_INSTALL) tzdata.zi
+
+posix_only: $(INSTALL_DATA_DEPS)
+		$(MAKE) $(INSTALLARGS) LEAPSECONDS= install_data
+
+right_only: $(INSTALL_DATA_DEPS)
+		$(MAKE) $(INSTALLARGS) LEAPSECONDS='-L leapseconds' \
+			install_data
+
+# In earlier versions of this makefile, the other two directories were
+# subdirectories of $(TZDIR).  However, this led to configuration errors.
+# For example, with posix_right under the earlier scheme,
+# TZ='right/Australia/Adelaide' got you localtime with leap seconds,
+# but gmtime without leap seconds, which led to problems with applications
+# like sendmail that subtract gmtime from localtime.
+# Therefore, the other two directories are now siblings of $(TZDIR).
+# You must replace all of $(TZDIR) to switch from not using leap seconds
+# to using them, or vice versa.
+right_posix:	right_only
+		rm -fr '$(DESTDIR)$(TZDIR)-leaps'
+		ln -s '$(TZDIR_BASENAME)' '$(DESTDIR)$(TZDIR)-leaps' || \
+		  $(MAKE) $(INSTALLARGS) TZDIR='$(TZDIR)-leaps' right_only
+		$(MAKE) $(INSTALLARGS) TZDIR='$(TZDIR)-posix' posix_only
+
+posix_right:	posix_only
+		rm -fr '$(DESTDIR)$(TZDIR)-posix'
+		ln -s '$(TZDIR_BASENAME)' '$(DESTDIR)$(TZDIR)-posix' || \
+		  $(MAKE) $(INSTALLARGS) TZDIR='$(TZDIR)-posix' posix_only
+		$(MAKE) $(INSTALLARGS) TZDIR='$(TZDIR)-leaps' right_only
+
+zones:		$(REDO)
+
+# dummy.zd is not a real file; it is mentioned here only so that the
+# top-level 'make' does not have a syntax error.
+ZDS = dummy.zd
+# Rule used only by submakes invoked by the $(TZS_NEW) rule.
+# It is separate so that GNU 'make -j' can run instances in parallel.
+$(ZDS): zdump
+		./zdump -i $(TZS_CUTOFF_FLAG) '$(wd)/'$$(expr $@ : '\(.*\).zd') \
+		  >$@
+
+TZS_NEW_DEPS = tzdata.zi zdump zic
+$(TZS_NEW): $(TZS_NEW_DEPS)
+		rm -fr tzs$(TZS_YEAR).dir
+		mkdir tzs$(TZS_YEAR).dir
+		$(zic) -d tzs$(TZS_YEAR).dir tzdata.zi
+		$(AWK) '/^L/{print "Link\t" $$2 "\t" $$3}' \
+		   tzdata.zi | LC_ALL=C sort >$@.out
+		wd=`pwd` && \
+		x=`$(AWK) '/^Z/{print "tzs$(TZS_YEAR).dir/" $$2 ".zd"}' \
+				tzdata.zi \
+			| LC_ALL=C sort -t . -k 2,2` && \
+		set x $$x && \
+		shift && \
+		ZDS=$$* && \
+		$(MAKE) wd="$$wd" TZS_CUTOFF_FLAG="$(TZS_CUTOFF_FLAG)" \
+		  ZDS="$$ZDS" $$ZDS && \
+		sed 's,^TZ=".*\.dir/,TZ=",' $$ZDS >>$@.out
+		rm -fr tzs$(TZS_YEAR).dir
+		mv $@.out $@
+
+# If $(TZS) exists but 'make check_tzs' fails, a maintainer should inspect the
+# failed output and fix the inconsistency, perhaps by running 'make force_tzs'.
+$(TZS):
+		touch $@
+
+force_tzs:	$(TZS_NEW)
+		cp $(TZS_NEW) $(TZS)
+
+libtz.a:	$(LIBOBJS)
+		rm -f $@
+		$(AR) -rc $@ $(LIBOBJS)
+		$(RANLIB) $@
+
+date:		$(DATEOBJS)
+		$(CC) -o $@ $(CFLAGS) $(LDFLAGS) $(DATEOBJS) $(LDLIBS)
+
+tzselect:	tzselect.ksh version
+		VERSION=`cat version` && sed \
+			-e 's|#!/bin/bash|#!$(KSHELL)|g' \
+			-e 's|AWK=[^}]*|AWK='\''$(AWK)'\''|g' \
+			-e 's|\(PKGVERSION\)=.*|\1='\''($(PACKAGE)) '\''|' \
+			-e 's|\(REPORT_BUGS_TO\)=.*|\1=$(BUGEMAIL)|' \
+			-e 's|TZDIR=[^}]*|TZDIR=$(TZDIR)|' \
+			-e 's|\(TZVERSION\)=.*|\1='"$$VERSION"'|' \
+			<$@.ksh >$@.out
+		chmod +x $@.out
+		mv $@.out $@
+
+check: check_back check_mild
+check_mild:	check_character_set check_white_space check_links \
+		  check_name_lengths check_slashed_abbrs check_sorted \
+		  check_tables check_web check_ziguard check_zishrink check_tzs
+
+check_character_set: $(ENCHILADA)
+	test ! '$(UTF8_LOCALE)' || \
+	! printf 'A\304\200B\n' | \
+	  LC_ALL='$(UTF8_LOCALE)' grep -q '^A.B$$' >/dev/null 2>&1 || { \
+		LC_ALL='$(UTF8_LOCALE)' && export LC_ALL && \
+		sharp='#' && \
+		! grep -Env $(SAFE_LINE) $(MANS) date.1 $(MANTXTS) \
+			$(MISC) $(SOURCES) $(WEB_PAGES) \
+			CONTRIBUTING LICENSE README SECURITY \
+			version tzdata.zi && \
+		! grep -Env $(SAFE_LINE)'|^UNUSUAL_OK_'$(OK_CHAR)'*$$' \
+			Makefile && \
+		! grep -Env $(SAFE_SHARP_LINE) $(TDATA_TO_CHECK) backzone \
+			leapseconds zone.tab && \
+		! grep -Env $(OK_LINE) $(ENCHILADA); \
+	}
+	touch $@
+
+check_white_space: $(ENCHILADA)
+		patfmt=' \t|[\f\r\v]' && pat=`printf "$$patfmt\\n"` && \
+		! grep -En "$$pat" \
+			$$(ls $(ENCHILADA) | grep -Fvx leap-seconds.list)
+		! grep -n '[$s]$$' \
+			$$(ls $(ENCHILADA) | grep -Fvx leap-seconds.list)
+		touch $@
+
+PRECEDES_FILE_NAME = ^(Zone|Link[$s]+[^$s]+)[$s]+
+FILE_NAME_COMPONENT_TOO_LONG = $(PRECEDES_FILE_NAME)[^$s]*[^/$s]{15}
+
+check_name_lengths: $(TDATA_TO_CHECK) backzone
+		! grep -En '$(FILE_NAME_COMPONENT_TOO_LONG)' \
+			$(TDATA_TO_CHECK) backzone
+		touch $@
+
+PRECEDES_STDOFF = ^(Zone[$s]+[^$s]+)?[$s]+
+STDOFF = [-+]?[0-9:.]+
+RULELESS_SAVE = (-|$(STDOFF)[sd]?)
+RULELESS_SLASHED_ABBRS = \
+  $(PRECEDES_STDOFF)$(STDOFF)[$s]+$(RULELESS_SAVE)[$s]+[^$s]*/
+
+check_slashed_abbrs: $(TDATA_TO_CHECK)
+		! grep -En '$(RULELESS_SLASHED_ABBRS)' $(TDATA_TO_CHECK)
+		touch $@
+
+CHECK_CC_LIST = { n = split($$1,a,/,/); for (i=2; i<=n; i++) print a[1], a[i]; }
+
+check_sorted: backward backzone iso3166.tab zone.tab zone1970.tab
+		$(AWK) '/^Link/ {printf "%.5d %s\n", g, $$3} !/./ {g++}' \
+		  backward | LC_ALL=C sort -cu
+		$(AWK) '/^Zone/ {print $$2}' backzone | LC_ALL=C sort -cu
+		touch $@
+
+check_back:	checklinks.awk $(TDATA_TO_CHECK)
+		$(AWK) \
+		  -v DATAFORM=$(DATAFORM) \
+		  -v backcheck=backward \
+		  -f checklinks.awk $(TDATA_TO_CHECK)
+		touch $@
+
+check_links:	checklinks.awk tzdata.zi
+		$(AWK) \
+		  -v DATAFORM=$(DATAFORM) \
+		  -f checklinks.awk tzdata.zi
+		touch $@
+
+check_tables:	checktab.awk $(YDATA) backward $(ZONETABLES)
+		for tab in $(ZONETABLES); do \
+		  test "$$tab" = zone.tab && links='$(BACKWARD)' || links=''; \
+		  $(AWK) -f checktab.awk -v zone_table=$$tab $(YDATA) $$links \
+		    || exit; \
+		done
+		touch $@
+
+check_tzs:	$(TZS) $(TZS_NEW)
+		if test -s $(TZS); then \
+		  $(DIFF_TZS) $(TZS) $(TZS_NEW); \
+		else \
+		  cp $(TZS_NEW) $(TZS); \
+		fi
+		touch $@
+
+check_web:	$(CHECK_WEB_PAGES)
+check_theory.html: theory.html
+check_tz-art.html: tz-art.html
+check_tz-how-to.html: tz-how-to.html
+check_tz-link.html: tz-link.html
+check_theory.html check_tz-art.html check_tz-how-to.html check_tz-link.html:
+		$(CURL) -sS --url https://validator.w3.org/nu/ -F out=gnu \
+		    -F file=@$$(expr $@ : 'check_\(.*\)') -o $@.out && \
+		  test ! -s $@.out || { cat $@.out; exit 1; }
+		mv $@.out $@
+
+check_ziguard: rearguard.zi vanguard.zi ziguard.awk
+		$(AWK) -v DATAFORM=rearguard -f ziguard.awk vanguard.zi | \
+		  diff -u rearguard.zi -
+		$(AWK) -v DATAFORM=vanguard -f ziguard.awk rearguard.zi | \
+		  diff -u vanguard.zi -
+		touch $@
+
+# Check that zishrink.awk does not alter the data, and that ziguard.awk
+# preserves main-format data.
+check_zishrink: check_zishrink_posix check_zishrink_right
+check_zishrink_posix check_zishrink_right: \
+  zic leapseconds $(PACKRATDATA) $(PACKRATLIST) \
+  $(TDATA) $(DATAFORM).zi tzdata.zi
+		rm -fr $@.dir $@-t.dir $@-shrunk.dir
+		mkdir $@.dir $@-t.dir $@-shrunk.dir
+		case $@ in \
+		  *_right) leap='-L leapseconds';; \
+		  *) leap=;; \
+		esac && \
+		  $(ZIC) $$leap -d $@.dir $(DATAFORM).zi && \
+		  $(ZIC) $$leap -d $@-shrunk.dir tzdata.zi && \
+		  case $(DATAFORM),$(PACKRATLIST) in \
+		    main,) \
+		      $(ZIC) $$leap -d $@-t.dir $(TDATA) && \
+		      $(AWK) '/^Rule/' $(TDATA) | \
+			$(ZIC) $$leap -d $@-t.dir - $(PACKRATDATA) && \
+		      diff -r $@.dir $@-t.dir;; \
+		  esac
+		diff -r $@.dir $@-shrunk.dir
+		rm -fr $@.dir $@-t.dir $@-shrunk.dir
+		touch $@
+
+clean_misc:
+		rm -fr check_*.dir
+		rm -f *.o *.out $(TIME_T_ALTERNATIVES) \
+		  check_* core typecheck_* \
+		  date tzselect version.h zdump zic libtz.a
+clean:		clean_misc
+		rm -fr *.dir tzdb-*/
+		rm -f *.zi $(TZS_NEW)
+
+maintainer-clean: clean
+		@echo 'This command is intended for maintainers to use; it'
+		@echo 'deletes files that may need special tools to rebuild.'
+		rm -f leapseconds version $(MANTXTS) $(TZS) *.asc *.tar.*
+
+names:
+		@echo $(ENCHILADA)
+
+public:		check check_public $(CHECK_TIME_T_ALTERNATIVES) \
+		tarballs signatures
+
+date.1.txt:	date.1
+newctime.3.txt:	newctime.3
+newstrftime.3.txt: newstrftime.3
+newtzset.3.txt:	newtzset.3
+time2posix.3.txt: time2posix.3
+tzfile.5.txt:	tzfile.5
+tzselect.8.txt:	tzselect.8
+zdump.8.txt:	zdump.8
+zic.8.txt:	zic.8
+
+$(MANTXTS):	workman.sh
+		LC_ALL=C sh workman.sh `expr $@ : '\(.*\)\.txt$$'` >$@.out
+		mv $@.out $@
+
+# Set file timestamps deterministically if possible,
+# so that tarballs containing the timestamps are reproducible.
+#
+# '$(SET_TIMESTAMP_N) N DEST A B C ...' sets the timestamp of the
+# file DEST to the maximum of the timestamps of the files A B C ...,
+# plus N if GNU ls and touch are available.
+SET_TIMESTAMP_N = sh -c '\
+  n=$$0 dest=$$1; shift; \
+  touch -cmr `ls -t "$$@" | sed 1q` "$$dest" && \
+  if test $$n != 0 && \
+     lsout=`ls -n --time-style="+%s" "$$dest" 2>/dev/null`; then \
+    set x $$lsout && \
+    touch -cmd @`expr $$7 + $$n` "$$dest"; \
+  else :; fi'
+# If DEST depends on A B C ... in this Makefile, callers should use
+# $(SET_TIMESTAMP_DEP) DEST A B C ..., for the benefit of any
+# downstream 'make' that considers equal timestamps to be out of date.
+# POSIX allows this 'make' behavior, and HP-UX 'make' does it.
+# If all that matters is that the timestamp be reproducible
+# and plausible, use $(SET_TIMESTAMP).
+SET_TIMESTAMP = $(SET_TIMESTAMP_N) 0
+SET_TIMESTAMP_DEP = $(SET_TIMESTAMP_N) 1
+
+# Set the timestamps to those of the git repository, if available,
+# and if the files have not changed since then.
+# This uses GNU 'ls --time-style=+%s', which outputs the seconds count,
+# and GNU 'touch -d@N FILE', where N is the number of seconds since 1970.
+# If git or GNU is absent, don't bother to sync with git timestamps.
+# Also, set the timestamp of each prebuilt file like 'leapseconds'
+# to be the maximum of the files it depends on.
+set-timestamps.out: $(EIGHT_YARDS)
+		rm -f $@
+		if (type git) >/dev/null 2>&1 && \
+		   files=`git ls-files $(EIGHT_YARDS)` && \
+		   touch -md @1 test.out; then \
+		  rm -f test.out && \
+		  for file in $$files; do \
+		    if git diff --quiet $$file; then \
+		      time=`git log -1 --format='tformat:%ct' $$file` && \
+		      touch -cmd @$$time $$file; \
+		    else \
+		      echo >&2 "$$file: warning: does not match repository"; \
+		    fi || exit; \
+		  done; \
+		fi
+		$(SET_TIMESTAMP_DEP) leapseconds $(LEAP_DEPS)
+		for file in `ls $(MANTXTS) | sed 's/\.txt$$//'`; do \
+		  $(SET_TIMESTAMP_DEP) $$file.txt $$file workman.sh || \
+		    exit; \
+		done
+		$(SET_TIMESTAMP_DEP) version $(VERSION_DEPS)
+		$(SET_TIMESTAMP_DEP) tzdata.zi $(TZDATA_ZI_DEPS)
+		touch $@
+set-tzs-timestamp.out: $(TZS)
+		$(SET_TIMESTAMP_DEP) $(TZS) $(TZS_DEPS)
+		touch $@
+
+# The zics below ensure that each data file can stand on its own.
+# We also do an all-files run to catch links to links.
+
+check_public: $(VERSION_DEPS)
+		rm -fr public.dir
+		mkdir public.dir
+		ln $(VERSION_DEPS) public.dir
+		cd public.dir && $(MAKE) CFLAGS='$(GCC_DEBUG_FLAGS)' ALL
+		for i in $(TDATA_TO_CHECK) public.dir/tzdata.zi \
+		    public.dir/vanguard.zi public.dir/main.zi \
+		    public.dir/rearguard.zi; \
+		do \
+		  public.dir/zic -v -d public.dir/zoneinfo $$i 2>&1 || exit; \
+		done
+		public.dir/zic -v -d public.dir/zoneinfo-all $(TDATA_TO_CHECK)
+		:
+		: Also check 'backzone' syntax.
+		rm public.dir/main.zi
+		cd public.dir && $(MAKE) PACKRATDATA=backzone main.zi
+		public.dir/zic -d public.dir/zoneinfo main.zi
+		rm public.dir/main.zi
+		cd public.dir && \
+		  $(MAKE) PACKRATDATA=backzone PACKRATLIST=zone.tab main.zi
+		public.dir/zic -d public.dir/zoneinfo main.zi
+		:
+		rm -fr public.dir
+		touch $@
+
+# Check that the code works under various alternative
+# implementations of time_t.
+check_time_t_alternatives: $(TIME_T_ALTERNATIVES)
+$(TIME_T_ALTERNATIVES_TAIL): $(TIME_T_ALTERNATIVES_HEAD)
+$(TIME_T_ALTERNATIVES): $(VERSION_DEPS)
+		rm -fr $@.dir
+		mkdir $@.dir
+		ln $(VERSION_DEPS) $@.dir
+		case $@ in \
+		  int*32_t) range=-2147483648,2147483648;; \
+		  u*) range=0,4294967296;; \
+		  *) range=-4294967296,4294967296;; \
+		esac && \
+		wd=`pwd` && \
+		zones=`$(AWK) '/^[^#]/ { print $$3 }' <zone1970.tab` && \
+		if test $@ = $(TIME_T_ALTERNATIVES_HEAD); then \
+		  range_target=; \
+		else \
+		  range_target=to$$range.tzs; \
+		fi && \
+		(cd $@.dir && \
+		  $(MAKE) TOPDIR="$$wd/$@.dir" \
+		    CFLAGS='$(CFLAGS) -Dtime_tz='"'$@'" \
+		    REDO='$(REDO)' \
+			D=$$wd/$@.dir \
+		    TZS_YEAR="$$range" TZS_CUTOFF_FLAG="-t $$range" \
+		    install $$range_target) && \
+		test $@ = $(TIME_T_ALTERNATIVES_HEAD) || { \
+		  (cd $(TIME_T_ALTERNATIVES_HEAD).dir && \
+		    $(MAKE) TOPDIR="$$wd/$@.dir" \
+		      TZS_YEAR="$$range" TZS_CUTOFF_FLAG="-t $$range" \
+			D=$$wd/$@.dir \
+		      to$$range.tzs) && \
+		  $(DIFF_TZS) $(TIME_T_ALTERNATIVES_HEAD).dir/to$$range.tzs \
+			  $@.dir/to$$range.tzs && \
+		  if diff -q Makefile Makefile 2>/dev/null; then \
+		    quiet_option='-q'; \
+		  else \
+		    quiet_option=''; \
+		  fi && \
+		    diff $$quiet_option -r $(TIME_T_ALTERNATIVES_HEAD).dir/etc \
+					   $@.dir/etc && \
+		    diff $$quiet_option -r \
+		      $(TIME_T_ALTERNATIVES_HEAD).dir/usr/share \
+		      $@.dir/usr/share; \
+		}
+		touch $@
+
+TRADITIONAL_ASC = \
+  tzcode$(VERSION).tar.gz.asc \
+  tzdata$(VERSION).tar.gz.asc
+REARGUARD_ASC = \
+  tzdata$(VERSION)-rearguard.tar.gz.asc
+ALL_ASC = $(TRADITIONAL_ASC) $(REARGUARD_ASC) \
+  tzdb-$(VERSION).tar.lz.asc
+
+tarballs rearguard_tarballs tailored_tarballs traditional_tarballs \
+signatures rearguard_signatures traditional_signatures: \
+  version set-timestamps.out rearguard.zi vanguard.zi
+		VERSION=`cat version` && \
+		$(MAKE) AWK='$(AWK)' VERSION="$$VERSION" $@_version
+
+# These *_version rules are intended for use if VERSION is set by some
+# other means.  Ordinarily these rules are used only by the above
+# non-_version rules, which set VERSION on the 'make' command line.
+tarballs_version: traditional_tarballs_version rearguard_tarballs_version \
+  tzdb-$(VERSION).tar.lz
+rearguard_tarballs_version: \
+  tzdata$(VERSION)-rearguard.tar.gz
+traditional_tarballs_version: \
+  tzcode$(VERSION).tar.gz tzdata$(VERSION).tar.gz
+tailored_tarballs_version: \
+  tzdata$(VERSION)-tailored.tar.gz
+signatures_version: $(ALL_ASC)
+rearguard_signatures_version: $(REARGUARD_ASC)
+traditional_signatures_version: $(TRADITIONAL_ASC)
+
+tzcode$(VERSION).tar.gz: set-timestamps.out
+		LC_ALL=C && export LC_ALL && \
+		tar $(TARFLAGS) -cf - \
+		    $(COMMON) $(DOCS) $(SOURCES) | \
+		  gzip $(GZIPFLAGS) >$@.out
+		mv $@.out $@
+
+tzdata$(VERSION).tar.gz: set-timestamps.out
+		LC_ALL=C && export LC_ALL && \
+		tar $(TARFLAGS) -cf - $(TZDATA_DIST) | \
+		  gzip $(GZIPFLAGS) >$@.out
+		mv $@.out $@
+
+# Create empty files with a reproducible timestamp.
+CREATE_EMPTY = TZ=UTC0 touch -mt 202010122253.00
+
+# The obsolescent *rearguard* targets and related macros are present
+# for backwards compatibility with tz releases 2018e through 2022a.
+# They should go away eventually.  To build rearguard tarballs you
+# can instead use 'make DATAFORM=rearguard tailored_tarballs'.
+tzdata$(VERSION)-rearguard.tar.gz: rearguard.zi set-timestamps.out
+		rm -fr $@.dir
+		mkdir $@.dir
+		ln $(TZDATA_DIST) $@.dir
+		cd $@.dir && rm -f $(TDATA) $(PACKRATDATA) version
+		for f in $(TDATA) $(PACKRATDATA); do \
+		  rearf=$@.dir/$$f; \
+		  $(AWK) -v DATAFORM=rearguard -f ziguard.awk $$f >$$rearf && \
+		  $(SET_TIMESTAMP_DEP) $$rearf ziguard.awk $$f || exit; \
+		done
+		sed '1s/$$/-rearguard/' <version >$@.dir/version
+		: The dummy pacificnew pacifies TZUpdater 2.3.1 and earlier.
+		$(CREATE_EMPTY) $@.dir/pacificnew
+		touch -cmr version $@.dir/version
+		LC_ALL=C && export LC_ALL && \
+		  (cd $@.dir && \
+		   tar $(TARFLAGS) -cf - \
+			$(TZDATA_DIST) pacificnew | \
+		     gzip $(GZIPFLAGS)) >$@.out
+		mv $@.out $@
+
+# Create a tailored tarball suitable for TZUpdater and compatible tools.
+# For example, 'make DATAFORM=vanguard tailored_tarballs' makes a tarball
+# useful for testing whether TZUpdater supports vanguard form.
+# The generated tarball is not byte-for-byte equivalent to a hand-tailored
+# traditional tarball, as data entries are put into 'etcetera' even if they
+# came from some other source file.  However, the effect should be the same
+# for ordinary use, which reads all the source files.
+tzdata$(VERSION)-tailored.tar.gz: set-timestamps.out
+		rm -fr $@.dir
+		mkdir $@.dir
+		: The dummy pacificnew pacifies TZUpdater 2.3.1 and earlier.
+		cd $@.dir && \
+		  $(CREATE_EMPTY) $(PRIMARY_YDATA) $(NDATA) backward \
+		  `test $(DATAFORM) = vanguard || echo pacificnew`
+		(grep '^#' tzdata.zi && echo && cat $(DATAFORM).zi) \
+		  >$@.dir/etcetera
+		touch -cmr tzdata.zi $@.dir/etcetera
+		sed -n \
+		  -e '/^# *version  *\(.*\)/h' \
+		  -e '/^# *ddeps  */H' \
+		  -e '$$!d' \
+		  -e 'g' \
+		  -e 's/^# *version  *//' \
+		  -e 's/\n# *ddeps  */-/' \
+		  -e 's/ /-/g' \
+		  -e 'p' \
+		  <tzdata.zi >$@.dir/version
+		touch -cmr version $@.dir/version
+		links= && \
+		  for file in $(TZDATA_DIST); do \
+		    test -f $@.dir/$$file || links="$$links $$file"; \
+		  done && \
+		  ln $$links $@.dir
+		LC_ALL=C && export LC_ALL && \
+		  (cd $@.dir && \
+		   tar $(TARFLAGS) -cf - * | gzip $(GZIPFLAGS)) >$@.out
+		mv $@.out $@
+
+tzdb-$(VERSION).tar.lz: set-timestamps.out set-tzs-timestamp.out
+		rm -fr tzdb-$(VERSION)
+		mkdir tzdb-$(VERSION)
+		ln $(ENCHILADA) tzdb-$(VERSION)
+		$(SET_TIMESTAMP) tzdb-$(VERSION) tzdb-$(VERSION)/*
+		LC_ALL=C && export LC_ALL && \
+		tar $(TARFLAGS) -cf - tzdb-$(VERSION) | lzip -9 >$@.out
+		mv $@.out $@
+
+tzcode$(VERSION).tar.gz.asc: tzcode$(VERSION).tar.gz
+tzdata$(VERSION).tar.gz.asc: tzdata$(VERSION).tar.gz
+tzdata$(VERSION)-rearguard.tar.gz.asc: tzdata$(VERSION)-rearguard.tar.gz
+tzdb-$(VERSION).tar.lz.asc: tzdb-$(VERSION).tar.lz
+$(ALL_ASC):
+		$(GPG) --armor --detach-sign $?
+
+TYPECHECK_CFLAGS = $(CFLAGS) -DTYPECHECK -D__time_t_defined -D_TIME_T
+typecheck: typecheck_long_long typecheck_unsigned
+typecheck_long_long typecheck_unsigned: $(VERSION_DEPS)
+		rm -fr $@.dir
+		mkdir $@.dir
+		ln $(VERSION_DEPS) $@.dir
+		cd $@.dir && \
+		  case $@ in \
+		    *_long_long) i="long long";; \
+		    *_unsigned ) i="unsigned" ;; \
+		  esac && \
+		  typecheck_cflags='' && \
+		  $(MAKE) \
+		    CFLAGS="$(TYPECHECK_CFLAGS) \"-Dtime_t=$$i\"" \
+		    TOPDIR="`pwd`" \
+		    install
+		$@.dir/zdump -i -c 1970,1971 Europe/Rome
+		touch $@
+
+zonenames:	tzdata.zi
+		@$(AWK) '/^Z/ { print $$2 } /^L/ { print $$3 }' tzdata.zi
+
+asctime.o:	private.h tzfile.h
+date.o:		private.h
+difftime.o:	private.h
+localtime.o:	private.h tzfile.h
+strftime.o:	private.h tzfile.h
+zdump.o:	version.h
+zic.o:		private.h tzfile.h version.h
+
+.PHONY: ALL INSTALL all
+.PHONY: check check_mild check_time_t_alternatives
+.PHONY: check_web check_zishrink
+.PHONY: clean clean_misc dummy.zd force_tzs
+.PHONY: install install_data maintainer-clean names
+.PHONY: posix_only posix_right public
+.PHONY: rearguard_signatures rearguard_signatures_version
+.PHONY: rearguard_tarballs rearguard_tarballs_version
+.PHONY: right_only right_posix signatures signatures_version
+.PHONY: tarballs tarballs_version
+.PHONY: traditional_signatures traditional_signatures_version
+.PHONY: traditional_tarballs traditional_tarballs_version
+.PHONY: tailored_tarballs tailored_tarballs_version
+.PHONY: typecheck
+.PHONY: zonenames zones
+.PHONY: $(ZDS)
diff --git a/contrib/tzcode/NEWS b/contrib/tzcode/NEWS
new file mode 100644
index 000000000000..701e490e4834
--- /dev/null
+++ b/contrib/tzcode/NEWS
@@ -0,0 +1,5902 @@
+News for the tz database
+
+Release 2022g - 2022-11-29 08:58:31 -0800
+
+  Briefly:
+    The northern edge of Chihuahua changes to US timekeeping.
+    Much of Greenland stops changing clocks after March 2023.
+    Fix some pre-1996 timestamps in northern Canada.
+    C89 is now deprecated; please use C99 or later.
+    Portability fixes for AIX, libintl, MS-Windows, musl, z/OS
+    In C code, use more C23 features if available.
+    C23 timegm now supported by default
+    Fixes for unlikely integer overflows
+
+  Changes to future timestamps
+
+    In the Mexican state of Chihuahua, the border strip near the US
+    will change to agree with nearby US locations on 2022-11-30.
+    The strip's western part, represented by Ciudad Juárez, switches
+    from -06 all year to -07/-06 with US DST rules, like El Paso, TX.
+    The eastern part, represented by Ojinaga, will observe US DST next
+    year, like Presidio, TX.  (Thanks to Heitor David Pinto.)
+    A new Zone America/Ciudad_Juarez splits from America/Ojinaga.
+
+    Much of Greenland, represented by America/Nuuk, stops observing
+    winter time after March 2023, so its daylight saving time becomes
+    standard time.  (Thanks to Jonas Nyrup and Jürgen Appel.)
+
+  Changes to past timestamps
+
+    Changes for pre-1996 northern Canada (thanks to Chris Walton):
+
+      Merge America/Iqaluit and America/Pangnirtung into the former,
+      with a backward compatibility link for the latter name.
+      There is no good evidence the two locations differ since 1970.
+      This change affects pre-1996 America/Pangnirtung timestamps.
+
+      Cambridge Bay, Inuvik, Iqaluit, Rankin Inlet, Resolute and
+      Yellowknife did not observe DST in 1965, and did observe DST
+      from 1972 through 1979.
+
+      Whitehorse moved from -09 to -08 on 1966-02-27, not 1967-05-28.
+
+    Colombia's 1993 fallback was 02-06 24:00, not 04-04 00:00.
+    (Thanks to Alois Treindl.)
+
+    Singapore's 1981-12-31 change was at 16:00 UTC (23:30 local time),
+    not 24:00 local time.  (Thanks to Geoff Clare via Robert Elz.)
+
+  Changes to code
+
+    Although tzcode still works with C89, bugs found in recent routine
+    maintenance indicate that bitrot has set in and that in practice
+    C89 is no longer used to build tzcode.  As it is a maintenance
+    burden, support for C89 is planned to be removed soon.  Instead,
+    please use compilers compatible with C99, C11, C17, or C23.
+
+    timegm, which tzcode implemented in 1989, will finally be
+    standardized 34 years later as part of C23, so timegm is now
+    supported even if STD_INSPIRED is not defined.
+
+    Fix bug in zdump's tzalloc emulation on hosts that lack tm_zone.
+    (Problem reported by Đoàn Trần Công Danh.)
+
+    Fix bug in zic on hosts where malloc(0) yields NULL on success.
+    (Problem reported by Tim McBrayer for AIX 6.1.)
+
+    Fix zic configuration to avoid linkage failures on some platforms.
+    (Problems reported by Gilmore Davidson and Igor Ivanov.)
+
+    Work around MS-Windows nmake incompatibility with POSIX.
+    (Problem reported by Manuela Friedrich.)
+
+    Port mktime and strftime to debugging platforms where accessing
+    uninitialized data has undefined behavior (strftime problem
+    reported by Robert Elz).
+
+    Check more carefully for unlikely integer overflows, preferring
+    C23 <stdckdint.h> to overflow checking by hand, as the latter has
+    had obscure bugs.
+
+  Changes to build procedure
+
+    New Makefile rule check_mild that skips checking whether Link
+    lines are in the file 'backward'.  (Inspired by a suggestion from
+    Stephen Colebourne.)
+
+
+Release 2022f - 2022-10-28 18:04:57 -0700
+
+  Briefly:
+    Mexico will no longer observe DST except near the US border.
+    Chihuahua moves to year-round -06 on 2022-10-30.
+    Fiji no longer observes DST.
+    Move links to 'backward'.
+    In vanguard form, GMT is now a Zone and Etc/GMT a link.
+    zic now supports links to links, and vanguard form uses this.
+    Simplify four Ontario zones.
+    Fix a Y2438 bug when reading TZif data.
+    Enable 64-bit time_t on 32-bit glibc platforms.
+    Omit large-file support when no longer needed.
+    In C code, use some C23 features if available.
+    Remove no-longer-needed workaround for Qt bug 53071.
+
+  Changes to future timestamps
+
+    Mexico will no longer observe DST after 2022, except for areas
+    near the US border that continue to observe US DST rules.
+    On 2022-10-30 at 02:00 the Mexican state of Chihuahua moves
+    from -07 (-06 with DST) to year-round -06, thus not changing
+    its clocks that day.  The new law states that Chihuahua
+    near the US border no longer observes US DST.
+    (Thanks to gera for the heads-up about Chihuahua.)
+
+    Fiji will not observe DST in 2022/3.  (Thanks to Shalvin Narayan.)
+    For now, assume DST is suspended indefinitely.
+
+  Changes to data
+
+    Move links to 'backward' to ease and simplify link maintenance.
+    This affects generated data only if you use 'make BACKWARD='.
+
+    GMT is now a Zone and Etc/GMT a link instead of vice versa,
+    as GMT is needed for leap second support whereas Etc/GMT is not.
+    However, this change exposes a bug in TZUpdater 2.3.2 so it is
+    present only in vanguard form for now.
+
+    Vanguard form now uses links to links, as zic now supports this.
+
+  Changes to past timestamps
+
+    Simplify four Ontario zones, as most of the post-1970 differences
+    seem to have been imaginary.  (Problem reported by Chris Walton.)
+    Move America/Nipigon, America/Rainy_River, and America/Thunder_Bay
+    to 'backzone'; backward-compatibility links still work, albeit
+    with some different timestamps before November 2005.
+
+  Changes to code
+
+    zic now supports links to links regardless of input line order.
+    For example, if Australia/Sydney is a Zone, the lines
+      Link Australia/Canberra Australia/ACT
+      Link Australia/Sydney Australia/Canberra
+    now work correctly, even though the shell commands
+      ln Australia/Canberra Australia/ACT
+      ln Australia/Sydney Australia/Canberra
+    would fail because the first command attempts to use a link
+    Australia/Canberra that does not exist until after the second
+    command is executed.  Previously, zic had unspecified behavior if
+    a Link line's target was another link, and zic often misbehaved if
+    a Link line's target was a later Link line.
+
+    Fix line number in zic's diagnostic for a link to a link.
+
+    Fix a bug that caused localtime to mishandle timestamps starting
+    in the year 2438 when reading data generated by 'zic -b fat' when
+    distant-future DST transitions occur at times given in standard
+    time or in UT, not the usual case of local time.  This occurs when
+    the corresponding .zi Rule lines specify DST transitions with TO
+    columns of 'max' and AT columns that end in 's' or 'u'.  The
+    number 2438 comes from the 32-bit limit in the year 2038, plus the
+    400-year Gregorian cycle.  (Problem reported by Bradley White.)
+
+    On glibc 2.34 and later, which optionally supports 64-bit time_t
+    on platforms like x86 where time_t was traditionally 32 bits,
+    default time_t to 64 instead of 32 bits.  This lets functions like
+    localtime support timestamps after the year 2038, and fixes
+    year-2038 problems in zic when accessing files dated after 2038.
+    To continue to limit time_t to 32 bits on these platforms, use
+    "make CFLAGS='-D_TIME_BITS=32'".
+
+    In C code, do not enable large-file support on platforms like AIX
+    and macOS that no longer need it now that tzcode does not use
+    off_t or related functions like 'stat'.  Large-file support is
+    still enabled by default on GNU/Linux, as it is needed for 64-bit
+    time_t support.
+
+    In C code, prefer C23 keywords to pre-C23 macros for alignof,
+    bool, false, and true.  Also, use the following C23 features if
+    available: __has_include, unreachable.
+
+    zic no longer works around Qt bug 53071, as the relevant Qt
+    releases have been out of support since 2019.  This change affects
+    only fat TZif files, as thin files never had the workaround.
+
+    zdump no longer modifies the environ vector when compiled on
+    platforms lacking tm_zone or when compiled with -DUSE_LTZ=0.
+    This avoid undefined behavior on POSIX platforms.
+
+
+Release 2022e - 2022-10-11 11:13:02 -0700
+
+  Briefly:
+    Jordan and Syria switch from +02/+03 with DST to year-round +03.
+
+  Changes to future timestamps
+
+    Jordan and Syria are abandoning the DST regime and are changing to
+    permanent +03, so they will not fall back from +03 to +02 on
+    2022-10-28.  (Thanks to Steffen Thorsen and Issam Al-Zuwairi.)
+
+  Changes to past timestamps
+
+    On 1922-01-01 Tijuana adopted standard time at 00:00, not 01:00.
+
+  Changes to past time zone abbreviations and DST flags
+
+    The temporary advancement of clocks in central Mexico in summer
+    1931 is now treated as daylight saving time, instead of as two
+    changes to standard time.
+
+
+Release 2022d - 2022-09-23 12:02:57 -0700
+
+  Briefly:
+    Palestine transitions are now Saturdays at 02:00.
+    Simplify three Ukraine zones into one.
+
+  Changes to future timestamps
+
+    Palestine now springs forward and falls back at 02:00 on the
+    first Saturday on or after March 24 and October 24, respectively.
+    This means 2022 falls back 10-29 at 02:00, not 10-28 at 01:00.
+    (Thanks to Heba Hamad.)
+
+  Changes to past timestamps
+
+    Simplify three Ukraine zones to one, since the post-1970
+    differences seem to have been imaginary.  Move Europe/Uzhgorod and
+    Europe/Zaporozhye to 'backzone'; backward-compatibility links
+    still work, albeit with different timestamps before October 1991.
+
+
+Release 2022c - 2022-08-15 17:47:18 -0700
+
+  Briefly:
+    Work around awk bug in FreeBSD, macOS, etc.
+    Improve tzselect on intercontinental Zones.
+
+  Changes to code
+
+    Work around a bug in onetrueawk that broke commands like
+    'make traditional_tarballs' on FreeBSD, macOS, etc.
+    (Problem reported by Deborah Goldsmith.)
+
+    Add code to tzselect that uses experimental structured comments in
+    zone1970.tab to clarify whether Zones like Africa/Abidjan and
+    Europe/Istanbul cross continent or ocean boundaries.
+    (Inspired by a problem reported by Peter Krefting.)
+
+    Fix bug with 'zic -d /a/b/c' when /a is unwritable but the
+    directory /a/b already exists.
+
+    Remove zoneinfo2tdf.pl, as it was unused and triggered false
+    malware alarms on some email servers.
+
+
+Release 2022b - 2022-08-10 15:38:32 -0700
+
+  Briefly:
+    Chile's DST is delayed by a week in September 2022.
+    Iran no longer observes DST after 2022.
+    Rename Europe/Kiev to Europe/Kyiv.
+    New zic -R option
+    Vanguard form now uses %z.
+    Finish moving duplicate-since-1970 zones to 'backzone'.
+    New build option PACKRATLIST
+    New tailored_tarballs target, replacing rearguard_tarballs
+
+  Changes to future timestamps
+
+    Chile's 2022 DST start is delayed from September 4 to September 11.
+    (Thanks to Juan Correa.)
+
+    Iran plans to stop observing DST permanently, after it falls back
+    on 2022-09-21.  (Thanks to Ali Mirjamali.)
+
+  Changes to past timestamps
+
+    Finish moving to 'backzone' the location-based zones whose
+    timestamps since 1970 are duplicates; adjust links accordingly.
+    This change ordinarily affects only pre-1970 timestamps, and with
+    the new PACKRATLIST option it does not affect any timestamps.
+    In this round the affected zones are Antarctica/Vostok,
+    Asia/Brunei, Asia/Kuala_Lumpur, Atlantic/Reykjavik,
+    Europe/Amsterdam, Europe/Copenhagen, Europe/Luxembourg,
+    Europe/Monaco, Europe/Oslo, Europe/Stockholm, Indian/Christmas,
+    Indian/Cocos, Indian/Kerguelen, Indian/Mahe, Indian/Reunion,
+    Pacific/Chuuk, Pacific/Funafuti, Pacific/Majuro, Pacific/Pohnpei,
+    Pacific/Wake and Pacific/Wallis, and the affected links are
+    Arctic/Longyearbyen, Atlantic/Jan_Mayen, Iceland, Pacific/Ponape,
+    Pacific/Truk, and Pacific/Yap.
+
+    From fall 1994 through fall 1995, Shanks wrote that Crimea's
+    DST transitions were at 02:00 standard time, not at 00:00.
+    (Thanks to Michael Deckers.)
+
+    Iran adopted standard time in 1935, not 1946.  In 1977 it observed
+    DST from 03-21 23:00 to 10-20 24:00; its 1978 transitions were on
+    03-24 and 08-05, not 03-20 and 10-20; and its spring 1979
+    transition was on 05-27, not 03-21.
+    (Thanks to Roozbeh Pournader and Francis Santoni.)
+
+    Chile's observance of -04 from 1946-08-29 through 1947-03-31 was
+    considered DST, not standard time.  Santiago and environs had moved
+    their clocks back to rejoin the rest of mainland Chile; put this
+    change at the end of 1946-08-28.  (Thanks to Michael Deckers.)
+
+    Some old, small clock transitions have been removed, as people at
+    the time did not change their clocks.  This affects Asia/Hong_Kong
+    in 1904, Asia/Ho_Chi_Minh in 1906, and Europe/Dublin in 1880.
+
+  Changes to zone name
+
+    Rename Europe/Kiev to Europe/Kyiv, as "Kyiv" is more common in
+    English now.  Spelling of other names in Ukraine has not yet
+    demonstrably changed in common English practice so for now these
+    names retain old spellings, as in other countries (e.g.,
+    Europe/Prague not "Praha", and Europe/Sofia not "Sofiya").
+
+  Changes to code
+
+    zic has a new option '-R @N' to output explicit transitions < N.
+    (Need suggested by Almaz Mingaleev.)
+
+    'zic -r @N' no longer outputs bad data when N < first transition.
+    (Problem introduced in 2021d and reported by Peter Krefting.)
+
+    zic now checks its input for NUL bytes and unterminated lines, and
+    now supports input line lengths up to 2048 (not 512) bytes.
+
+    gmtime and related code now use the abbreviation "UTC" not "GMT".
+    POSIX is being revised to require this.
+
+    When tzset and related functions set vestigial static variables
+    like tzname, they now prefer specified timestamps to unspecified ones.
+    (Problem reported by Almaz Mingaleev.)
+
+    zic no longer complains "can't determine time zone abbreviation to
+    use just after until time" when a transition to a new standard
+    time occurs simultaneously with the first DST fallback transition.
+
+  Changes to build procedure
+
+    Source data in vanguard form now uses the %z notation, introduced
+    in release 2015f.  For example, for America/Sao_Paulo vanguard
+    form contains the zone continuation line "-3:00 Brazil %z", which
+    is simpler and more reliable than the line "-3:00 Brazil -03/-02"
+    used in main and rearguard forms.  The plan is for the main form
+    to use %z eventually; in the meantime maintainers of zi parsers
+    are encouraged to test the parsers on vanguard.zi.
+
+    The Makefile has a new PACKRATLIST option to select a subset of
+    'backzone'.  For example, 'make PACKRATDATA=backzone
+    PACKRATLIST=zone.tab' now generates TZif files identical to those
+    of the global-tz project.
+
+    The Makefile has a new tailored_tarballs target for generating
+    special-purpose tarballs.  It generalizes and replaces the
+    rearguard_tarballs target and related targets and macros, which
+    are now obsolescent.
+
+    'make install' now defaults LOCALTIME to Factory not GMT,
+    which means the default abbreviation is now "-00" not "GMT".
+
+    Remove the posix_packrat target, marked obsolescent in 2016a.
+
+
+Release 2022a - 2022-03-15 23:02:01 -0700
+
+  Briefly:
+    Palestine will spring forward on 2022-03-27, not -03-26.
+    zdump -v now outputs better failure indications.
+    Bug fixes for code that reads corrupted TZif data.
+
+  Changes to future timestamps
+
+    Palestine will spring forward on 2022-03-27, not 2022-03-26.
+    (Thanks to Heba Hamad.)  Predict future transitions for first
+    Sunday >= March 25.  Additionally, predict fallbacks to be the first
+    Friday on or after October 23, not October's last Friday, to be more
+    consistent with recent practice.  The first differing fallback
+    prediction is on 2025-10-24, not 2025-10-31.
+
+  Changes to past timestamps
+
+    From 1992 through spring 1996, Ukraine's DST transitions were at
+    02:00 standard time, not at 01:00 UTC.  (Thanks to Alois Treindl.)
+
+    Chile's Santiago Mean Time and its LMT precursor have been adjusted
+    eastward by 1 second to align with past and present law.
+
+  Changes to commentary
+
+    Add several references for Chile's 1946/1947 transitions, some of
+    which only affected portions of the country.
+
+  Changes to code
+
+    Fix bug when mktime gets confused by truncated TZif files with
+    unspecified local time.  (Problem reported by Almaz Mingaleev.)
+
+    Fix bug when 32-bit time_t code reads malformed 64-bit TZif data.
+    (Problem reported by Christos Zoulas.)
+
+    When reading a version 2 or later TZif file, the TZif reader now
+    validates the version 1 header and data block only enough to skip
+    over them, as recommended by RFC 8536 section 4.  Also, the TZif
+    reader no longer mistakenly attempts to parse a version 1 TZIf
+    file header as a TZ string.
+
+    zdump -v now outputs "(localtime failed)" and "(gmtime failed)"
+    when local time and UT cannot be determined for a timestamp.
+
+  Changes to build procedure
+
+    Distribution tarballs now use standard POSIX.1-1988 ustar format
+    instead of GNU format.  Although the formats are almost identical
+    for these tarballs, ustar headers' magic fields contain "ustar"
+    instead of "ustar ", and their version fields contain "00" instead
+    of " ".  The two formats are planned to diverge more significantly
+    for tzdb releases after 2242-03-16 12:56:31 UTC, when the ustar
+    format becomes obsolete and the tarballs switch to pax format, an
+    extension of ustar.  For details about these formats, please see
+    "pax - portable archive interchange", IEEE Std 1003.1-2017,
+    <https://pubs.opengroup.org/onlinepubs/9699919799/utilities/pax.html#tag_20_92_13>.
+
+
+Release 2021e - 2021-10-21 18:41:00 -0700
+
+  Changes to future timestamps
+
+    Palestine will fall back 10-29 (not 10-30) at 01:00.
+    (Thanks to P Chan and Heba Hemad.)
+
+
+Release 2021d - 2021-10-15 13:48:18 -0700
+
+  Briefly:
+    Fiji suspends DST for the 2021/2022 season.
+    'zic -r' marks unspecified timestamps with "-00".
+
+  Changes to future timestamps
+
+    Fiji will suspend observance of DST for the 2021/2022 season.
+    Assume for now that it will return next year.  (Thanks to Jashneel
+    Kumar and P Chan.)
+
+  Changes to code
+
+    'zic -r' now uses "-00" time zone abbreviations for intervals
+    with UT offsets that are unspecified due to -r truncation.
+    This implements a change in draft Internet RFC 8536bis.
+
+
+Release 2021c - 2021-10-01 14:21:49 -0700
+
+  Briefly:
+    Revert most 2021b changes to 'backward'.
+    Fix 'zic -b fat' bug in pre-1970 32-bit data.
+    Fix two Link line typos.
+    Distribute SECURITY file.
+
+    This release is intended as a bugfix release, to fix compatibility
+    problems and typos reported since 2021b was released.
+
+  Changes to Link directives
+
+    Revert almost all of 2021b's changes to the 'backward' file,
+    by moving Link directives back to where they were in 2021a.
+    Although 'zic' doesn't care which source file contains a Link
+    directive, some downstream uses ran into trouble with the move.
+    (Problem reported by Stephen Colebourne for Joda-Time.)
+
+    Fix typo that linked Atlantic/Jan_Mayen to the wrong location
+    (problem reported by Chris Walton).
+
+    Fix 'backzone' typo that linked America/Virgin to the wrong
+    location (problem reported by Michael Deckers).
+
+  Changes to code
+
+    Fix a bug in 'zic -b fat' that caused old timestamps to be
+    mishandled in 32-bit-only readers (problem reported by Daniel
+    Fischer).
+
+  Changes to documentation
+
+    Distribute the SECURITY file (problem reported by Andreas Radke).
+
+
+Release 2021b - 2021-09-24 16:23:00 -0700
+
+  Briefly:
+    Jordan now starts DST on February's last Thursday.
+    Samoa no longer observes DST.
+    Merge more location-based Zones whose timestamps agree since 1970.
+    Move some backward-compatibility links to 'backward'.
+    Rename Pacific/Enderbury to Pacific/Kanton.
+    Correct many pre-1993 transitions in Malawi, Portugal, etc.
+    zic now creates each output file or link atomically.
+    zic -L no longer omits the POSIX TZ string in its output.
+    zic fixes for truncation and leap second table expiration.
+    zic now follows POSIX for TZ strings using all-year DST.
+    Fix some localtime crashes and bugs in obscure cases.
+    zdump -v now outputs more-useful boundary cases.
+    tzfile.5 better matches a draft successor to RFC 8536.
+    A new file SECURITY.
+
+    This release is prompted by recent announcements by Jordan and Samoa.
+    It incorporates many other changes that had accumulated since 2021a.
+    However, it omits most proposed changes that merged all Zones
+    agreeing since 1970, as concerns were raised about doing too many of
+    these changes at once.  It does keeps some of these changes in the
+    interest of making tzdb more equitable one step at a time; see
+    "Merge more location-based Zones" below.
+
+  Changes to future timestamps
+
+    Jordan now starts DST on February's last Thursday.
+    (Thanks to Steffen Thorsen.)
+
+    Samoa no longer observes DST.  (Thanks to Geoffrey D. Bennett.)
+
+  Changes to zone name
+
+    Rename Pacific/Enderbury to Pacific/Kanton.  When we added
+    Enderbury in 1993, we did not know that it is uninhabited and that
+    Kanton (population two dozen) is the only inhabited location in
+    that timezone.  The old name is now a backward-compatibility link.
+
+  Changes to past timestamps
+
+    Correct many pre-1993 transitions, fixing entries originally
+    derived from Shanks, Whitman, and Mundell.  The fixes include:
+      - Barbados: standard time was introduced in 1911, not 1932; and
+	DST was observed in 1942-1944
+      - Cook Islands: In 1899 they switched from east to west of GMT,
+	celebrating Christmas for two days.  They (and Niue) switched
+	to standard time in 1952, not 1901.
+      - Guyana: corrected LMT for Georgetown; the introduction of
+	standard time in 1911, not 1915; and corrections to 1975 and
+	1992 transitions
+      - Kanton: uninhabited before 1937-08-31
+      - Niue: only observed -11:20 from 1952 through 1964, then went to
+        -11 instead of -11:30
+      - Portugal: DST was observed in 1950
+      - Tonga: corrected LMT; the introduction of standard time in 1945,
+        not 1901; and corrections to the transition from +12:20 to +13
+        in 1961, not 1941
+    Additional fixes to entries in the 'backzone' file include:
+      - Enderbury: inhabited only 1860/1885 and 1938-03-06/1942-02-09
+      - The Gambia: 1933 and 1942 transitions
+      - Malawi: several 1911 through 1925 transitions
+      - Sierra Leone: several 1913 through 1941 transitions, and DST
+	was NOT observed in 1957 through 1962
+    (Thanks to P Chan, Michael Deckers, Alexander Krivenyshev and
+    Alois Treindl.)
+
+    Merge more location-based Zones whose timestamps agree since 1970,
+    as pre-1970 timestamps are out of scope.  This is part of a
+    process that has been ongoing since 2013.  This does not affect
+    post-1970 timestamps, and timezone historians who build with 'make
+    PACKRATDATA=backzone' should see no changes to pre-1970 timestamps.
+    When merging, keep the most-populous location's data, and move
+    data for other locations to 'backzone' with a backward
+    link in 'backward'.  For example, move America/Creston data to
+    'backzone' with a link in 'backward' from America/Phoenix because
+    the two timezones' timestamps agree since 1970; this change
+    affects some pre-1968 timestamps in America/Creston because
+    Creston and Phoenix disagreed before 1968.  The affected Zones
+    are Africa/Accra, America/Atikokan, America/Blanc-Sablon,
+    America/Creston, America/Curacao, America/Nassau,
+    America/Port_of_Spain, Antarctica/DumontDUrville, and
+    Antarctica/Syowa.
+
+  Changes to maintenance procedure
+
+    The new file SECURITY covers how to report security-related bugs.
+
+    Several backward-compatibility links have been moved to the
+    'backward' file.  These links, which range from Africa/Addis_Ababa
+    to Pacific/Saipan, are only for compatibility with now-obsolete
+    guidelines suggesting an entry for every ISO 3166 code.
+    The intercontinental convenience links Asia/Istanbul and
+    Europe/Nicosia have also been moved to 'backward'.
+
+  Changes to code
+
+    zic now creates each output file or link atomically,
+    possibly by creating a temporary file and then renaming it.
+    This avoids races where a TZ setting would temporarily stop
+    working while zic was installing a replacement file or link.
+
+    zic -L no longer omits the POSIX TZ string in its output.
+    Starting with 2020a, zic -L truncated its output according to the
+    "Expires" directive or "#expires" comment in the leapseconds file.
+    The resulting TZif files omitted daylight saving transitions after
+    the leap second table expired, which led to far less-accurate
+    predictions of times after the expiry.  Although future timestamps
+    cannot be converted accurately in the presence of leap seconds, it
+    is more accurate to convert near-future timestamps with a few
+    seconds error than with an hour error, so zic -L no longer
+    truncates output in this way.
+
+    Instead, when zic -L is given the "Expires" directive, it now
+    outputs the expiration by appending a no-change entry to the leap
+    second table.  Although this should work well with most TZif
+    readers, it does not conform to Internet RFC 8536 and some pickier
+    clients (including tzdb 2017c through 2021a) reject it, so
+    "Expires" directives are currently disabled by default.  To enable
+    them, set the EXPIRES_LINE Makefile variable.  If a TZif file uses
+    this new feature it is marked with a new TZif version number 4,
+    a format intended to be documented in a successor to RFC 8536.
+
+    zic -L LEAPFILE -r @LO no longer generates an invalid TZif file
+    that omits leap second information for the range LO..B when LO
+    falls between two leap seconds A and B.  Instead, it generates a
+    TZif version 4 file that represents the previously-missing
+    information.
+
+    The TZif reader now allows the leap second table to begin with a
+    correction other than -1 or +1, and to contain adjacent
+    transitions with equal corrections.  This supports TZif version 4.
+
+    The TZif reader now lets leap seconds occur less than 28 days
+    apart.  This supports possible future TZif extensions.
+
+    Fix bug that caused 'localtime' etc. to crash when TZ was
+    set to a all-year DST string like "EST5EDT4,0/0,J365/25" that does
+    not conform to POSIX but does conform to Internet RFC 8536.
+
+    Fix another bug that caused 'localtime' etc. to crash when TZ was
+    set to a POSIX-conforming but unusual TZ string like
+    "EST5EDT4,0/0,J365/0", where almost all the year is DST.
+
+    Fix yet another bug that caused 'localtime' etc. to mishandle slim
+    TZif files containing leap seconds after the last explicit
+    transition in the table, or when handling far-future timestamps
+    in slim TZif files lacking leap seconds.
+
+    Fix localtime misbehavior involving positive leap seconds.
+    This change affects only behavior for "right" system time,
+    which contains leap seconds, and only if the UT offset is
+    not a multiple of 60 seconds when a positive leap second occurs.
+    (No such timezone exists in tzdb, luckily.)  Without the fix,
+    the timestamp was ambiguous during a positive leap second.
+    With the fix, any seconds occurring after a positive leap second
+    and within the same localtime minute are counted through 60, not
+    through 59; their UT offset (tm_gmtoff) is the same as before.
+    Here is how the fix affects timestamps in a timezone with UT
+    offset +01:23:45 (5025 seconds) and with a positive leap second at
+    1972-06-30 23:59:60 UTC (78796800):
+
+	time_t    without the fix      with the fix
+	78796800  1972-07-01 01:23:45  1972-07-01 01:23:45 (leap second)
+	78796801  1972-07-01 01:23:45  1972-07-01 01:23:46
+	...
+	78796815  1972-07-01 01:23:59  1972-07-01 01:23:60
+	78796816  1972-07-01 01:24:00  1972-07-01 01:24:00
+
+    Fix an unlikely bug that caused 'localtime' etc. to misbehave if
+    civil time changes a few seconds before time_t wraps around, when
+    leap seconds are enabled.
+
+    Fix bug in zic -r; in some cases, the dummy time type after the
+    last time transition disagreed with the TZ string, contrary to
+    Internet RFC 8563 section 3.3.
+
+    Fix a bug with 'zic -r @X' when X is a negative leap second that
+    has a nonnegative correction.  Without the fix, the output file
+    was truncated so that X appeared to be a positive leap second.
+    Fix a similar, even-less-likely bug when truncating at a positive
+    leap second that has a nonpositive correction.
+
+    zic -r now reports an error if given rolling leap seconds, as this
+    usage has never generally worked and is evidently unused.
+
+    zic now generates a POSIX-conforming TZ string for TZif files
+    where all-year DST is predicted for the indefinite future.
+    For example, for all-year Eastern Daylight Time, zic now generates
+    "XXX3EDT4,0/0,J365/23" where it previously generated
+    "EST5EDT,0/0,J365/25" or "".  (Thanks to Michael Deckers for
+    noting the possibility of POSIX conformance.)
+
+    zic.c no longer requires sys/wait.h (thanks to spazmodius for
+    noting it wasn't needed).
+
+    When reading slim TZif files, zdump no longer mishandles leap
+    seconds on the rare platforms where time_t counts leap seconds,
+    fixing a bug introduced in 2014g.
+
+    zdump -v now outputs timestamps at boundaries of what localtime
+    and gmtime can represent, instead of the less-useful timestamps
+    one day after the minimum and one day before the maximum.
+    (Thanks to Arthur David Olson for prototype code, and to Manuela
+    Friedrich for debugging help.)
+
+    zdump's -c and -t options are now consistently inclusive for the
+    lower time bound and exclusive for the upper.  Formerly they were
+    inconsistent.  (Confusion noted by Martin Burnicki.)
+
+  Changes to build procedure
+
+    You can now compile with -DHAVE_MALLOC_ERRNO=0 to port to
+    non-POSIX hosts where malloc doesn't set errno.
+    (Problem reported by Jan Engelhardt.)
+
+  Changes to documentation
+
+    tzfile.5 better matches a draft successor to RFC 8536
+    <https://datatracker.ietf.org/doc/draft-murchison-rfc8536bis/01/>.
+
+
+Release 2021a - 2021-01-24 10:54:57 -0800
+
+  Changes to future timestamps
+
+    South Sudan changes from +03 to +02 on 2021-02-01 at 00:00.
+    (Thanks to Steffen Thorsen.)
+
+
+Release 2020f - 2020-12-29 00:17:46 -0800
+
+  Change to build procedure
+
+    'make rearguard_tarballs' no longer generates a bad rearguard.zi,
+    fixing a 2020e bug.  (Problem reported by Deborah Goldsmith.)
+
+
+Release 2020e - 2020-12-22 15:14:34 -0800
+
+  Briefly:
+    Volgograd switches to Moscow time on 2020-12-27 at 02:00.
+
+  Changes to future timestamps
+
+    Volgograd changes time zone from +04 to +03 on 2020-12-27 at 02:00.
+    (Thanks to Alexander Krivenyshev and Stepan Golosunov.)
+
+  Changes to past timestamps
+
+    Correct many pre-1986 transitions, fixing entries originally
+    derived from Shanks.  The fixes include:
+      - Australia: several 1917 through 1971 transitions
+      - The Bahamas: several 1941 through 1945 transitions
+      - Bermuda: several 1917 through 1956 transitions
+      - Belize: several 1942 through 1968 transitions
+      - Ghana: several 1915 through 1956 transitions
+      - Israel and Palestine: several 1940 through 1985 transitions
+      - Kenya and adjacent: several 1908 through 1960 transitions
+      - Nigeria and adjacent: correcting LMT in Lagos, and several 1905
+        through 1919 transitions
+      - Seychelles: the introduction of standard time in 1907, not 1906
+      - Vanuatu: DST in 1973-1974, and a corrected 1984 transition
+    (Thanks to P Chan.)
+
+    Because of the Australia change, Australia/Currie (King Island) is
+    no longer needed, as it is identical to Australia/Hobart for all
+    timestamps since 1970 and was therefore created by mistake.
+    Australia/Currie has been moved to the 'backward' file and its
+    corrected data moved to the 'backzone' file.
+
+  Changes to past time zone abbreviations and DST flags
+
+    To better match legislation in Turks and Caicos, the 2015 shift to
+    year-round observance of -04 is now modeled as AST throughout before
+    returning to Eastern Time with US DST in 2018, rather than as
+    maintaining EDT until 2015-11-01.  (Thanks to P Chan.)
+
+  Changes to documentation
+
+    The zic man page now documents zic's coalescing of transitions
+    when a zone falls back just before DST springs forward.
+
+
+Release 2020d - 2020-10-21 11:24:13 -0700
+
+  Briefly:
+    Palestine ends DST earlier than predicted, on 2020-10-24.
+
+  Changes to past and future timestamps
+
+    Palestine ends DST on 2020-10-24 at 01:00, instead of 2020-10-31
+    as previously predicted (thanks to Sharef Mustafa.)  Its
+    2019-10-26 fall-back was at 00:00, not 01:00 (thanks to Steffen
+    Thorsen.)  Its 2015-10-23 transition was at 01:00 not 00:00, and
+    its spring 2020 transition was on March 28 at 00:00, not March 27
+    (thanks to Pierre Cashon.)  This affects Asia/Gaza and
+    Asia/Hebron.  Assume future spring and fall transitions will be on
+    the Saturday preceding the last Sunday of March and October,
+    respectively.
+
+
+Release 2020c - 2020-10-16 11:15:53 -0700
+
+  Briefly:
+    Fiji starts DST later than usual, on 2020-12-20.
+
+  Changes to future timestamps
+
+    Fiji will start DST on 2020-12-20, instead of 2020-11-08 as
+    previously predicted.  DST will still end on 2021-01-17.
+    (Thanks to Raymond Kumar and Alan Mintz.)  Assume for now that
+    the later-than-usual start date is a one-time departure from the
+    recent pattern.
+
+  Changes to build procedure
+
+    Rearguard tarballs now contain an empty file pacificnew.
+    Some older downstream software expects this file to exist.
+    (Problem reported by Mike Cullinan.)
+
+
+Release 2020b - 2020-10-06 18:35:04 -0700
+
+  Briefly:
+    Revised predictions for Morocco's changes starting in 2023.
+    Canada's Yukon changes to -07 on 2020-11-01, not 2020-03-08.
+    Macquarie Island has stayed in sync with Tasmania since 2011.
+    Casey, Antarctica is at +08 in winter and +11 in summer.
+    zic no longer supports -y, nor the TYPE field of Rules.
+
+  Changes to future timestamps
+
+    Morocco's spring-forward after Ramadan is now predicted to occur
+    no sooner than two days after Ramadan, instead of one day.
+    (Thanks to Milamber.)  The first altered prediction is for 2023,
+    now predicted to spring-forward on April 30 instead of April 23.
+
+  Changes to past and future timestamps
+
+   Casey Station, Antarctica has been using +08 in winter and +11 in
+   summer since 2018.  The most recent transition from +08 to +11 was
+   2020-10-04 00:01.  Also, Macquarie Island has been staying in
+   sync with Tasmania since 2011.  (Thanks to Steffen Thorsen.)
+
+  Changes to past and future time zone abbreviations and DST flags
+
+    Canada's Yukon, represented by America/Whitehorse and
+    America/Dawson, changes its time zone rules from -08/-07 to
+    permanent -07 on 2020-11-01, not on 2020-03-08 as 2020a had it.
+    This change affects only the time zone abbreviation (MST vs PDT)
+    and daylight saving flag for the period between the two dates.
+    (Thanks to Andrew G. Smith.)
+
+  Changes to past timestamps
+
+    Correct several transitions for Hungary for 1918/1983.
+    For example, the 1983-09-25 fall-back was at 01:00, not 03:00.
+    (Thanks to Géza Nyáry.)  Also, the 1890 transition to standard
+    time was on 11-01, not 10-01 (thanks to Michael Deckers).
+
+    The 1891 French transition was on March 16, not March 15.  The
+    1911-03-11 French transition was at midnight, not a minute later.
+    Monaco's transitions were on 1892-06-01 and 1911-03-29, not
+    1891-03-15 and 1911-03-11.  (Thanks to Michael Deckers.)
+
+  Changes to code
+
+    Support for zic's long-obsolete '-y YEARISTYPE' option has been
+    removed and, with it, so has support for the TYPE field in Rule
+    lines, which is now reserved for compatibility with earlier zic.
+    These features were previously deprecated in release 2015f.
+    (Thanks to Tim Parenti.)
+
+    zic now defaults to '-b slim' instead of to '-b fat'.
+
+    zic's new '-l -' and '-p -' options uninstall any existing
+    localtime and posixrules files, respectively.
+
+    The undocumented and ineffective tzsetwall function has been
+    removed.
+
+  Changes to build procedure
+
+    The Makefile now defaults POSIXRULES to '-', so the posixrules
+    feature (obsolete as of 2019b) is no longer installed by default.
+
+  Changes to documentation and commentary
+
+    The long-obsolete files pacificnew, systemv, and yearistype.sh have
+    been removed from the distribution.  (Thanks to Tim Parenti.)
+
+
+Release 2020a - 2020-04-23 16:03:47 -0700
+
+  Briefly:
+    Morocco springs forward on 2020-05-31, not 2020-05-24.
+    Canada's Yukon advanced to -07 year-round on 2020-03-08.
+    America/Nuuk renamed from America/Godthab.
+    zic now supports expiration dates for leap second lists.
+
+  Changes to future timestamps
+
+    Morocco's second spring-forward transition in 2020 will be May 31,
+    not May 24 as predicted earlier.  (Thanks to Semlali Naoufal.)
+    Adjust future-year predictions to use the first Sunday after the
+    day after Ramadan, not the first Sunday after Ramadan.
+
+    Canada's Yukon, represented by America/Whitehorse and
+    America/Dawson, advanced to -07 year-round, beginning with its
+    spring-forward transition on 2020-03-08, and will not fall back on
+    2020-11-01.  Although a government press release calls this
+    "permanent Pacific Daylight Saving Time", we prefer MST for
+    consistency with nearby Dawson Creek, Creston, and Fort Nelson.
+    (Thanks to Tim Parenti.)
+
+  Changes to past timestamps
+
+    Shanghai observed DST in 1919.  (Thanks to Phake Nick.)
+
+  Changes to timezone identifiers
+
+    To reflect current usage in English better, America/Godthab has
+    been renamed to America/Nuuk.  A backwards-compatibility link
+    remains for the old name.
+
+  Changes to code
+
+    localtime.c no longer mishandles timestamps after the last
+    transition in a TZif file with leap seconds and with daylight
+    saving time transitions projected into the indefinite future.
+    For example, with TZ='America/Los_Angeles' with leap seconds,
+    zdump formerly reported a DST transition on 2038-03-14
+    from 01:59:32.999... to 02:59:33 instead of the correct transition
+    from 01:59:59.999... to 03:00:00.
+
+    zic -L now supports an Expires line in the leapseconds file, and
+    truncates the TZif output accordingly.  This propagates leap
+    second expiration information into the TZif file, and avoids the
+    abovementioned localtime.c bug as well as similar bugs present in
+    many client implementations.  If no Expires line is present, zic
+    -L instead truncates the TZif output based on the #expires comment
+    present in leapseconds files distributed by tzdb 2018f and later;
+    however, this usage is obsolescent.  For now, the distributed
+    leapseconds file has an Expires line that is commented out, so
+    that the file can be fed to older versions of zic which ignore the
+    commented-out line.  Future tzdb distributions are planned to
+    contain a leapseconds file with an Expires line.
+
+    The configuration macros HAVE_TZNAME and USG_COMPAT should now be
+    set to 1 if the system library supports the feature, and 2 if not.
+    As before, these macros are nonzero if tzcode should support the
+    feature, zero otherwise.
+
+    The configuration macro ALTZONE now has the same values with the
+    same meaning as HAVE_TZNAME and USG_COMPAT.
+
+    The code's defense against CRLF in leap-seconds.list is now
+    portable to POSIX awk.  (Problem reported by Deborah Goldsmith.)
+
+    Although the undocumented tzsetwall function is not changed in
+    this release, it is now deprecated in preparation for removal in
+    future releases.  Due to POSIX requirements, tzsetwall has not
+    worked for some time.  Any code that uses it should instead use
+    tzalloc(NULL) or, if portability trumps thread-safety, should
+    unset the TZ environment variable.
+
+  Changes to commentary
+
+    The Îles-de-la-Madeleine and the Listuguj reserve are noted as
+    following America/Halifax, and comments about Yukon's "south" and
+    "north" have been corrected to say "east" and "west".  (Thanks to
+    Jeffery Nichols.)
+
+
+Release 2019c - 2019-09-11 08:59:48 -0700
+
+  Briefly:
+    Fiji observes DST from 2019-11-10 to 2020-01-12.
+    Norfolk Island starts observing Australian-style DST.
+
+  Changes to future timestamps
+
+    Fiji's next DST transitions will be 2019-11-10 and 2020-01-12
+    instead of 2019-11-03 and 2020-01-19.  (Thanks to Raymond Kumar.)
+    Adjust future guesses accordingly.
+
+    Norfolk Island will observe Australian-style DST starting in
+    spring 2019.  The first transition is on 2019-10-06.  (Thanks to
+    Kyle Czech and Michael Deckers.)
+
+  Changes to past timestamps
+
+    Many corrections to time in Turkey from 1940 through 1985.
+    (Thanks to Oya Vulaş via Alois Treindl, and to Kıvanç Yazan.)
+
+    The Norfolk Island 1975-03-02 transition was at 02:00 standard
+    time, not 02:00 DST.  (Thanks to Michael Deckers.)
+
+    South Korea observed DST from 1948 through 1951.  Although this
+    info was supposed to appear in release 2014j, a typo inadvertently
+    suppressed the change.  (Thanks to Alois Treindl.)
+
+    Detroit observed DST in 1967 and 1968 following the US DST rules,
+    except that its 1967 DST began on June 14 at 00:01.  (Thanks to
+    Alois Treindl for pointing out that the old data entries were
+    probably wrong.)
+
+    Fix several errors in pre-1970 transitions in Perry County, IN.
+    (Thanks to Alois Treindl for pointing out the 1967/9 errors.)
+
+    Edmonton did not observe DST in 1967 or 1969.  In 1946 Vancouver
+    ended DST on 09-29 not 10-13, and Vienna ended DST on 10-07 not
+    10-06.  In 1945 Königsberg (now Kaliningrad) switched from +01/+02
+    to +02/+03 on 04-10 not 01-01, and its +02/+03 is abbreviated
+    EET/EEST, not CET/CEST.  (Thanks to Alois Treindl.)  In 1946
+    Königsberg switched to +03 on 04-07 not 01-01.
+
+    In 1946 Louisville switched from CST to CDT on 04-28 at 00:01, not
+    01-01 at 00:00.  (Thanks to Alois Treindl and Michael Deckers.)
+    Also, it switched from CST to CDT on 1950-04-30, not 1947-04-27.
+
+    The 1892-05-01 transition in Brussels was at 00:17:30, not at noon.
+    (Thanks to Michael Deckers.)
+
+  Changes to past time zone abbreviations and DST flags
+
+    Hong Kong Winter Time, observed from 1941-10-01 to 1941-12-25,
+    is now flagged as DST and is abbreviated HKWT not HKT.
+
+  Changes to code
+
+    leapseconds.awk now relies only on its input data, rather than
+    also relying on its comments.  (Inspired by code from Dennis
+    Ferguson and Chris Woodbury.)
+
+    The code now defends against CRLFs in leap-seconds.list.
+    (Thanks to Brian Inglis and Chris Woodbury.)
+
+  Changes to documentation and commentary
+
+    theory.html discusses leap seconds.  (Thanks to Steve Summit.)
+
+    Nashville's newspapers dueled about the time of day in the 1950s.
+    (Thanks to John Seigenthaler.)
+
+    Liechtenstein observed Swiss DST in 1941/2.
+    (Thanks to Alois Treindl.)
+
+
+Release 2019b - 2019-07-01 00:09:53 -0700
+
+  Briefly:
+    Brazil no longer observes DST.
+    'zic -b slim' outputs smaller TZif files; please try it out.
+    Palestine's 2019 spring-forward transition was on 03-29, not 03-30.
+
+  Changes to future timestamps
+
+    Brazil has canceled DST and will stay on standard time indefinitely.
+    (Thanks to Steffen Thorsen, Marcus Diniz, and Daniel Soares de
+    Oliveira.)
+
+    Predictions for Morocco now go through 2087 instead of 2037, to
+    work around a problem on newlib when using TZif files output by
+    zic 2019a or earlier.  (Problem reported by David Gauchard.)
+
+  Changes to past and future timestamps
+
+    Palestine's 2019 spring transition was 03-29 at 00:00, not 03-30
+    at 01:00.  (Thanks to Sharef Mustafa and Even Scharning.)  Guess
+    future transitions to be March's last Friday at 00:00.
+
+  Changes to past timestamps
+
+    Hong Kong's 1941-06-15 spring-forward transition was at 03:00, not
+    03:30.  Its 1945 transition from JST to HKT was on 11-18 at 02:00,
+    not 09-15 at 00:00.  In 1946 its spring-forward transition was on
+    04-21 at 00:00, not the previous day at 03:30.  From 1946 through
+    1952 its fall-back transitions occurred at 04:30, not at 03:30.
+    In 1947 its fall-back transition was on 11-30, not 12-30.
+    (Thanks to P Chan.)
+
+  Changes to past time zone abbreviations
+
+    Italy's 1866 transition to Rome Mean Time was on December 12, not
+    September 22.  This affects only the time zone abbreviation for
+    Europe/Rome between those dates.  (Thanks to Stephen Trainor and
+    Luigi Rosa.)
+
+  Changes affecting metadata only
+
+    Add info about the Crimea situation in zone1970.tab and zone.tab.
+    (Problem reported by Serhii Demediuk.)
+
+  Changes to code
+
+    zic's new -b option supports a way to control data bloat and to
+    test for year-2038 bugs in software that reads TZif files.
+    'zic -b fat' and 'zic -b slim' generate larger and smaller output;
+    for example, changing from fat to slim shrinks the Europe/London
+    file from 3648 to 1599 bytes, saving about 56%.  Fat and slim
+    files represent the same set of timestamps and use the same TZif
+    format as documented in tzfile(5) and in Internet RFC 8536.
+    Fat format attempts to work around bugs or incompatibilities in
+    older software, notably software that mishandles 64-bit TZif data
+    or uses obsolete TZ strings like "EET-2EEST" that lack DST rules.
+    Slim format is more efficient and does not work around 64-bit bugs
+    or obsolete TZ strings.  Currently zic defaults to fat format
+    unless you compile with -DZIC_BLOAT_DEFAULT=\"slim\"; this
+    out-of-the-box default is intended to change in future releases
+    as the buggy software often mishandles timestamps anyway.
+
+    zic no longer treats a set of rules ending in 2037 specially.
+    Previously, zic assumed that such a ruleset meant that future
+    timestamps could not be predicted, and therefore omitted a
+    POSIX-like TZ string in the TZif output.  The old behavior is no
+    longer needed for current tzdata, and caused problems with newlib
+    when used with older tzdata (reported by David Gauchard).
+
+    zic no longer generates some artifact transitions.  For example,
+    Europe/London no longer has a no-op transition in January 1996.
+
+  Changes to build procedure
+
+    tzdata.zi now assumes zic 2017c or later.  This shrinks tzdata.zi
+    by a percent or so.
+
+  Changes to documentation and commentary
+
+    The Makefile now documents the POSIXRULES macro as being obsolete,
+    and similarly, zic's -p POSIXRULES option is now documented as
+    being obsolete.  Although the POSIXRULES feature still exists and
+    works as before, in practice it is rarely used for its intended
+    purpose, and it does not work either in the default reference
+    implementation (for timestamps after 2037) or in common
+    implementations such as GNU/Linux (for contemporary timestamps).
+    Since POSIXRULES was designed primarily as a temporary transition
+    facility for System V platforms that died off decades ago, it is
+    being decommissioned rather than institutionalized.
+
+    New info on Bonin Islands and Marcus (thanks to Wakaba and Phake Nick).
+
+
+Release 2019a - 2019-03-25 22:01:33 -0700
+
+  Briefly:
+    Palestine "springs forward" on 2019-03-30 instead of 2019-03-23.
+    Metlakatla "fell back" to rejoin Alaska Time on 2019-01-20 at 02:00.
+
+  Changes to past and future timestamps
+
+    Palestine will not start DST until 2019-03-30, instead of 2019-03-23 as
+    previously predicted.  Adjust our prediction by guessing that spring
+    transitions will be between 24 and 30 March, which matches recent practice
+    since 2016.  (Thanks to Even Scharning and Tim Parenti.)
+
+    Metlakatla ended its observance of Pacific standard time,
+    rejoining Alaska Time, on 2019-01-20 at 02:00.  (Thanks to Ryan
+    Stanley and Tim Parenti.)
+
+  Changes to past timestamps
+
+    Israel observed DST in 1980 (08-02/09-13) and 1984 (05-05/08-25).
+    (Thanks to Alois Treindl and Isaac Starkman.)
+
+  Changes to time zone abbreviations
+
+    Etc/UCT is now a backward-compatibility link to Etc/UTC, instead
+    of being a separate zone that generates the abbreviation "UCT",
+    which nowadays is typically a typo.  (Problem reported by Isiah
+    Meadows.)
+
+  Changes to code
+
+    zic now has an -r option to limit the time range of output data.
+    For example, 'zic -r @1000000000' limits the output data to
+    timestamps starting 1000000000 seconds after the Epoch.
+    This helps shrink output size and can be useful for applications
+    not needing the full timestamp history, such as TZDIST truncation;
+    see Internet RFC 8536 section 5.1.  (Inspired by a feature request
+    from Christopher Wong, helped along by bug reports from Wong and
+    from Tim Parenti.)
+
+  Changes to documentation
+
+    Mention Internet RFC 8536 (February 2019), which documents TZif.
+
+    tz-link.html now cites tzdata-meta
+    <https://tzdata-meta.timtimeonline.com/>.
+
+
+Release 2018i - 2018-12-30 11:05:43 -0800
+
+  Briefly:
+    São Tomé and Príncipe switches from +01 to +00 on 2019-01-01.
+
+  Changes to future timestamps
+
+    Due to a change in government, São Tomé and Príncipe switches back
+    from +01 to +00 on 2019-01-01 at 02:00.  (Thanks to Vadim
+    Nasardinov and Michael Deckers.)
+
+
+Release 2018h - 2018-12-23 17:59:32 -0800
+
+  Briefly:
+    Qyzylorda, Kazakhstan moved from +06 to +05 on 2018-12-21.
+    New zone Asia/Qostanay because Qostanay, Kazakhstan didn't move.
+    Metlakatla, Alaska observes PST this winter only.
+    Guess Morocco will continue to adjust clocks around Ramadan.
+    Add predictions for Iran from 2038 through 2090.
+
+  Changes to future timestamps
+
+    Guess that Morocco will continue to fall back just before and
+    spring forward just after Ramadan, the practice since 2012.
+    (Thanks to Maamar Abdelkader.)  This means Morocco will observe
+    negative DST during Ramadan in main and vanguard formats, and in
+    rearguard format it stays in the +00 timezone and observes
+    ordinary DST in all months other than Ramadan.  As before, extend
+    this guesswork to the year 2037.  As a consequence, Morocco is
+    scheduled to observe three DST transitions in some Gregorian years
+    (e.g., 2033) due to the mismatch between the Gregorian and Islamic
+    calendars.
+
+    The table of exact transitions for Iranian DST has been extended.
+    It formerly cut off before the year 2038 in a nod to 32-bit time_t.
+    It now cuts off before 2091 as there is doubt about how the Persian
+    calendar will treat 2091.  This change predicts DST transitions in
+    2038-9, 2042-3, and 2046-7 to occur one day later than previously
+    predicted.  As before, post-cutoff transitions are approximated.
+
+  Changes to past and future timestamps
+
+    Qyzylorda (aka Kyzylorda) oblast in Kazakhstan moved from +06 to
+    +05 on 2018-12-21.  This is a zone split as Qostanay (aka
+    Kostanay) did not switch, so create a zone Asia/Qostanay.
+
+    Metlakatla moved from Alaska to Pacific standard time on 2018-11-04.
+    It did not change clocks that day and remains on -08 this winter.
+    (Thanks to Ryan Stanley.)  It will revert to the usual Alaska
+    rules next spring, so this change affects only timestamps
+    from 2018-11-04 through 2019-03-10.
+
+  Change to past timestamps
+
+    Kwajalein's 1993-08-20 transition from -12 to +12 was at 24:00,
+    not 00:00.  I transcribed the time incorrectly from Shanks.
+    (Thanks to Phake Nick.)
+
+    Nauru's 1979 transition was on 02-10 at 02:00, not 05-01 at 00:00.
+    (Thanks to Phake Nick.)
+
+    Guam observed DST irregularly from 1959 through 1977.
+    (Thanks to Phake Nick.)
+
+    Hong Kong observed DST in 1941 starting 06-15 (not 04-01), then on
+    10-01 changed standard time to +08:30 (not +08).  Its transition
+    back to +08 after WWII was on 1945-09-15, not the previous day.
+    Its 1904-10-30 change took effect at 01:00 +08 (not 00:00 LMT).
+    (Thanks to Phake Nick, Steve Allen, and Joseph Myers.)  Also,
+    its 1952 fallback was on 11-02 (not 10-25).
+
+    This release contains many changes to timestamps before 1946 due
+    to Japanese possession or occupation of Pacific/Chuuk,
+    Pacific/Guam, Pacific/Kosrae, Pacific/Kwajalein, Pacific/Majuro,
+    Pacific/Nauru, Pacific/Palau, and Pacific/Pohnpei.
+    (Thanks to Phake Nick.)
+
+    Assume that the Spanish East Indies was like the Philippines and
+    observed American time until the end of 1844.  This affects
+    Pacific/Chuuk, Pacific/Kosrae, Pacific/Palau, and Pacific/Pohnpei.
+
+  Changes to past tm_isdst flags
+
+    For the recent Morocco change, the tm_isdst flag should be 1 from
+    2018-10-27 00:00 to 2018-10-28 03:00.  (Thanks to Michael Deckers.)
+    Give a URL to the official decree.  (Thanks to Matt Johnson.)
+
+
+Release 2018g - 2018-10-26 22:22:45 -0700
+
+  Briefly:
+    Morocco switches to permanent +01 on 2018-10-28.
+
+  Changes to future timestamps
+
+    Morocco switches from +00/+01 to permanent +01 effective 2018-10-28,
+    so its clocks will not fall back as previously scheduled.
+    (Thanks to Mohamed Essedik Najd and Brian Inglis.)
+
+  Changes to code
+
+    When generating TZif files with leap seconds, zic no longer uses a
+    format that trips up older 32-bit clients, fixing a bug introduced
+    in 2018f.  (Reported by Daniel Fischer.)  Also, the zic workaround
+    for QTBUG-53071 now also works for TZif files with leap seconds.
+
+    The translator to rearguard format now rewrites the line
+    "Rule Japan 1948 1951 - Sep Sat>=8 25:00 0 S" to
+    "Rule Japan 1948 1951 - Sep Sun>=9  1:00 0 S".
+    This caters to zic before 2007 and to Oracle TZUpdater 2.2.0
+    and earlier.  (Reported by Christos Zoulas.)
+
+  Changes to past time zone abbreviations
+
+    Change HDT to HWT/HPT for WWII-era abbreviations in Hawaii.
+    This reverts to 2011h, as the abbreviation change in 2011i was
+    likely inadvertent.
+
+  Changes to documentation
+
+    tzfile.5 has new sections on interoperability issues.
+
+
+Release 2018f - 2018-10-18 00:14:18 -0700
+
+  Briefly:
+  Volgograd moves from +03 to +04 on 2018-10-28.
+  Fiji ends DST 2019-01-13, not 2019-01-20.
+  Most of Chile changes DST dates, effective 2019-04-06.
+
+  Changes to future timestamps
+
+    Volgograd moves from +03 to +04 on 2018-10-28 at 02:00.
+    (Thanks to Alexander Fetisov and Stepan Golosunov.)
+
+    Fiji ends DST 2019-01-13 instead of the 2019-01-20 previously
+    predicted.  (Thanks to Raymond Kumar.)  Adjust future predictions
+    accordingly.
+
+    Most of Chile will end DST on the first Saturday in April at 24:00 mainland
+    time, and resume DST on the first Saturday in September at 24:00 mainland
+    time.  The changes are effective from 2019-04-06, and do not affect the
+    Magallanes region modeled by America/Punta_Arenas.  (Thanks to Juan Correa
+    and Tim Parenti.)  Adjust future predictions accordingly.
+
+  Changes to past timestamps
+
+    The 2018-05-05 North Korea 30-minute time zone change took place
+    at 23:30 the previous day, not at 00:00 that day.
+
+    China's 1988 spring-forward transition was on April 17, not
+    April 10.  Its DST transitions in 1986/91 were at 02:00, not 00:00.
+    (Thanks to P Chan.)
+
+    Fix several issues for Macau before 1992.  Macau's pre-1904 LMT
+    was off by 10 s.  Macau switched to +08 in 1904 not 1912, and
+    temporarily switched to +09/+10 during World War II.  Macau
+    observed DST in 1942/79, not 1961/80, and there were several
+    errors for transition times and dates.  (Thanks to P Chan.)
+
+    The 1948-1951 fallback transitions in Japan were at 25:00 on
+    September's second Saturday, not at 24:00.  (Thanks to Phake Nick.)
+    zic turns this into 01:00 on the day after September's second
+    Saturday, which is the best that POSIX or C platforms can do.
+
+    Incorporate 1940-1949 Asia/Shanghai DST transitions from a 2014
+    paper by Li Yu, replacing more-questionable data from Shanks.
+
+  Changes to time zone abbreviations
+
+    Use "PST" and "PDT" for Philippine time.  (Thanks to Paul Goyette.)
+
+  Changes to code
+
+    zic now always generates TZif files where time type 0 is used for
+    timestamps before the first transition.  This simplifies the
+    reading of TZif files and should not affect behavior of existing
+    TZif readers because the same set of time types is used; only
+    their internal indexes may have changed.  This affects only the
+    legacy zones EST5EDT, CST6CDT, MST7MDT, PST8PDT, CET, MET, and
+    EET, which previously used nonzero types for these timestamps.
+
+    Because of the type 0 change, zic no longer outputs a dummy
+    transition at time -2**59 (before the Big Bang), as clients should
+    no longer need this to handle historical timestamps correctly.
+    This reverts a change introduced in 2013d and shrinks most TZif
+    files by a few bytes.
+
+    zic now supports negative time-of-day in Rule and Leap lines, e.g.,
+    "Rule X min max - Apr lastSun -6:00 1:00 -" means the transition
+    occurs at 18:00 on the Saturday before the last Sunday in April.
+    This behavior was documented in 2018a but the code did not
+    entirely match the documentation.
+
+    localtime.c no longer requires at least one time type in TZif
+    files that lack transitions or have a POSIX-style TZ string.  This
+    future-proofs the code against possible future extensions to the
+    format that would allow TZif files with POSIX-style TZ strings and
+    without transitions or time types.
+
+    A read-access subscript error in localtime.c has been fixed.
+    It could occur only in TZif files with timecnt == 0, something that
+    does not happen in practice now but could happen in future versions.
+
+    localtime.c no longer ignores TZif POSIX-style TZ strings that
+    specify only standard time.  Instead, these TZ strings now
+    override the default time type for timestamps after the last
+    transition (or for all timestamps if there are no transitions),
+    just as DST strings specifying DST have always done.
+
+    leapseconds.awk now outputs "#updated" and "#expires" comments,
+    and supports leap seconds at the ends of months other than June
+    and December.  (Inspired by suggestions from Chris Woodbury.)
+
+  Changes to documentation
+
+    New restrictions: A Rule name must start with a character that
+    is neither an ASCII digit nor "-" nor "+", and an unquoted name
+    should not use characters in the set "!$%&'()*,/:;<=>?@[\]^`{|}~".
+    The latter restriction makes room for future extensions (a
+    possibility noted by Tom Lane).
+
+    tzfile.5 now documents what time types apply before the first and
+    after the last transition, if any.
+
+    Documentation now uses the spelling "timezone" for a TZ setting
+    that determines timestamp history, and "time zone" for a
+    geographic region currently sharing the same standard time.
+
+    The name "TZif" is now used for the tz binary data format.
+
+    tz-link.htm now mentions the A0 TimeZone Migration utilities.
+    (Thanks to Aldrin Martoq for the link.)
+
+  Changes to build procedure
+
+    New 'make' target 'rearguard_tarballs' to build the rearguard
+    tarball only.  This is a convenience on platforms that lack lzip
+    if you want to build the rearguard tarball.  (Problem reported by
+    Deborah Goldsmith.)
+
+    tzdata.zi is now more stable from release to release.  (Problem
+    noted by Tom Lane.)  It is also a bit shorter.
+
+    tzdata.zi now can contain comment lines documenting configuration
+    information, such as which data format was selected, which input
+    files were used, and how leap seconds are treated.  (Problems
+    noted by Lester Caine and Brian Inglis.)  If the Makefile defaults
+    are used these comment lines are absent, for backward
+    compatibility.  A redistributor intending to alter its copy of the
+    files should also append "-LABEL" to the 'version' file's first
+    line, where "LABEL" identifies the redistributor's change.
+
+
+Release 2018e - 2018-05-01 23:42:51 -0700
+
+  Briefly:
+
+    North Korea switches back to +09 on 2018-05-05.
+    The main format uses negative DST again, for Ireland etc.
+    'make tarballs' now also builds a rearguard tarball.
+    New 's' and 'd' suffixes in SAVE columns of Rule and Zone lines.
+
+  Changes to past and future timestamps
+
+    North Korea switches back from +0830 to +09 on 2018-05-05.
+    (Thanks to Kang Seonghoon, Arthur David Olson, Seo Sanghyeon,
+    and Tim Parenti.)
+
+    Bring back the negative-DST changes of 2018a, except be more
+    compatible with data parsers that do not support negative DST.
+    Also, this now affects historical timestamps in Namibia and the
+    former Czechoslovakia, not just Ireland.  The main format now uses
+    negative DST to model timestamps in Europe/Dublin (from 1971 on),
+    Europe/Prague (1946/7), and Africa/Windhoek (1994/2017).  This
+    does not affect UT offsets, only time zone abbreviations and the
+    tm_isdst flag.  Also, this does not affect rearguard or vanguard
+    formats; effectively the main format now uses vanguard instead of
+    rearguard format.  Data parsers that do not support negative DST
+    can still use data from the rearguard tarball described below.
+
+  Changes to build procedure
+
+    The command 'make tarballs' now also builds the tarball
+    tzdataVERSION-rearguard.tar.gz, which is like tzdataVERSION.tar.gz
+    except that it uses rearguard format intended for trailing-edge
+    data parsers.
+
+  Changes to data format and to code
+
+    The SAVE column of Rule and Zone lines can now have an 's' or 'd'
+    suffix, which specifies whether the adjusted time is standard time
+    or daylight saving time.  If no suffix is given, daylight saving
+    time is used if and only if the SAVE column is nonzero; this is
+    the longstanding behavior.  Although this new feature is not used
+    in tzdata, it could be used to specify the legal time in Namibia
+    1994-2017, as opposed to the popular time (see below).
+
+  Changes to past timestamps
+
+    From 1994 through 2017 Namibia observed DST in winter, not summer.
+    That is, it used negative DST, as Ireland still does.  This change
+    does not affect UTC offsets; it affects only the tm_isdst flag and
+    the abbreviation used during summer, which is now CAT, not WAST.
+    Although (as noted by Michael Deckers) summer and winter time were
+    both simply called "standard time" in Namibian law, in common
+    practice winter time was considered to be DST (as noted by Stephen
+    Colebourne).  The full effect of this change is only in vanguard
+    and main format; in rearguard format, the tm_isdst flag is still
+    zero in winter and nonzero in summer.
+
+    In 1946/7 Czechoslovakia also observed negative DST in winter.
+    The full effect of this change is only in vanguard and main
+    formats; in rearguard format, it is modeled as plain GMT without
+    daylight saving.  Also, the dates of some 1944/5 DST transitions
+    in Czechoslovakia have been changed.
+
+
+Release 2018d - 2018-03-22 07:05:46 -0700
+
+  Briefly:
+
+  Palestine starts DST a week earlier in 2018.
+  Add support for vanguard and rearguard data consumers.
+  Add subsecond precision to source data format, though not to data.
+
+  Changes to future timestamps
+
+    In 2018, Palestine starts DST on March 24, not March 31.
+    Adjust future predictions accordingly.  (Thanks to Sharef Mustafa.)
+
+  Changes to past and future timestamps
+
+    Casey Station in Antarctica changed from +11 to +08 on 2018-03-11
+    at 04:00.  (Thanks to Steffen Thorsen.)
+
+  Changes to past timestamps
+
+    Historical transitions for Uruguay, represented by
+    America/Montevideo, have been updated per official legal documents,
+    replacing previous data mainly originating from the inventions of
+    Shanks & Pottenger.  This has resulted in adjustments ranging from
+    30 to 90 minutes in either direction over at least two dozen
+    distinct periods ranging from one day to several years in length.
+    A mere handful of pre-1991 transitions are unaffected; data since
+    then has come from more reliable contemporaneous reporting.  These
+    changes affect various timestamps in 1920-1923, 1936, 1939,
+    1942-1943, 1959, 1966-1970, 1972, 1974-1980, and 1988-1990.
+    Additionally, Uruguay's pre-standard-time UT offset has been
+    adjusted westward by 7 seconds, from UT-03:44:44 to UT-03:44:51, to
+    match the location of the Observatory of the National Meteorological
+    Institute in Montevideo.
+    (Thanks to Jeremie Bonjour, Tim Parenti, and Michael Deckers.)
+
+    East Kiribati skipped New Year's Eve 1994, not New Year's Day 1995.
+    (Thanks to Kerry Shetline.)
+
+    Fix the 1912-01-01 transition for Portugal and its colonies.
+    This transition was at 00:00 according to the new UT offset, not
+    according to the old one.  Also assume that Cape Verde switched on
+    the same date as the rest, not in 1907.  This affects
+    Africa/Bissau, Africa/Sao_Tome, Asia/Macau, Atlantic/Azores,
+    Atlantic/Cape_Verde, Atlantic/Madeira, and Europe/Lisbon.
+    (Thanks to Michael Deckers.)
+
+    Fix an off-by-1 error for pre-1913 timestamps in Jamaica and in
+    Turks & Caicos.
+
+  Changes to past time zone abbreviations
+
+    MMT took effect in Uruguay from 1908-06-10, not 1898-06-28.  There
+    is no clock change associated with the transition.
+
+  Changes to build procedure
+
+    The new DATAFORM macro in the Makefile lets the installer choose
+    among three source data formats.  The idea is to lessen downstream
+    disruption when data formats are improved.
+
+    * DATAFORM=vanguard installs from the latest, bleeding-edge
+      format.  DATAFORM=main (the default) installs from the format
+      used in the 'africa' etc. files.  DATAFORM=rearguard installs
+      from a trailing-edge format.  Eventually, elements of today's
+      vanguard format should move to the main format, and similarly
+      the main format's features should eventually move to the
+      rearguard format.
+
+    * In the current version, the main and rearguard formats are
+      identical and match that of 2018c, so this change does not
+      affect default behavior.  The vanguard format currently contains
+      one feature not in the main format: negative SAVE values.  This
+      improves support for Ireland, which uses Irish Standard Time
+      (IST, UTC+01) in summer and GMT (UTC) in winter.  tzcode has
+      supported negative SAVE values for decades, and this feature
+      should move to the main format soon.  However, it will not move
+      to the rearguard format for quite some time because some
+      downstream parsers do not support it.
+
+    * The build procedure constructs three files vanguard.zi, main.zi,
+      and rearguard.zi, one for each format.  Although the files
+      represent essentially the same data, they may have minor
+      discrepancies that users are not likely to notice.  The files
+      are intended for downstream data consumers and are not
+      installed.  Zoneinfo parsers that do not support negative SAVE values
+      should start using rearguard.zi, so that they will be unaffected
+      when the negative-DST feature moves from vanguard to main.
+      Bleeding-edge Zoneinfo parsers that support the new features
+      already can use vanguard.zi; in this respect, current tzcode is
+      bleeding-edge.
+
+    The Makefile should now be safe for parallelized builds, and 'make
+    -j to2050new.tzs' is now much faster on a multiprocessor host
+    with GNU Make.
+
+    When built with -DSUPPRESS_TZDIR, the tzcode library no longer
+    prepends TZDIR/ to file names that do not begin with '/'.  This is
+    not recommended for general use, due to its security implications.
+    (From a suggestion by Manuela Friedrich.)
+
+  Changes to code
+
+    zic now accepts subsecond precision in expressions like
+    00:19:32.13, which is approximately the legal time of the
+    Netherlands from 1835 to 1937.  However, because it is
+    questionable whether the few recorded uses of non-integer offsets
+    had subsecond precision in practice, there are no plans for tzdata
+    to use this feature.  (Thanks to Steve Allen for pointing out
+    the limitations of historical data in this area.)
+
+    The code is a bit more portable to MS-Windows.  Installers can
+    compile with -DRESERVE_STD_EXT_IDS on MS-Windows platforms that
+    reserve identifiers like 'localtime'.  (Thanks to Manuela
+    Friedrich.)
+
+  Changes to documentation and commentary
+
+    theory.html now outlines tzdb's extensions to POSIX's model for
+    civil time, and has a section "POSIX features no longer needed"
+    that lists POSIX API components that are now vestigial.
+    (From suggestions by Steve Summit.)  It also better distinguishes
+    time zones from tz regions.  (From a suggestion by Guy Harris.)
+
+    Commentary is now more consistent about using the phrase "daylight
+    saving time", to match the C name tm_isdst.  Daylight saving time
+    need not occur in summer, and need not have a positive offset from
+    standard time.
+
+    Commentary about historical transitions in Uruguay has been expanded
+    with links to many relevant legal documents.
+    (Thanks to Tim Parenti.)
+
+    Commentary now uses some non-ASCII characters with Unicode value
+    less than U+0100, as they can be useful and should work even with
+    older editors such as XEmacs.
+
+
+Release 2018c - 2018-01-22 23:00:44 -0800
+
+  Briefly:
+  Revert Irish changes that relied on negative SAVE values.
+
+  Changes to tm_isdst
+
+    Revert the 2018a change to Europe/Dublin.  As before, this change
+    does not affect UT offsets or abbreviations; it affects only
+    whether timestamps are considered to be standard time or
+    daylight-saving time, as expressed in the tm_isdst flag of C's
+    struct tm type.  This reversion is intended to be a temporary
+    workaround for problems discovered with downstream uses of
+    releases 2018a and 2018b, which implemented Irish time by using
+    negative SAVE values in the Eire rules of the 'europe' file.
+    Although negative SAVE values have been part of tzcode for many
+    years and are supported by many platforms, they were not
+    documented before 2018a and ICU and OpenJDK do not currently
+    support them.  A mechanism to export data to platforms lacking
+    support for negative DST is planned to be developed before the
+    change is reapplied.  (Problems reported by Deborah Goldsmith and
+    Stephen Colebourne.)
+
+  Changes to past timestamps
+
+    Japanese DST transitions (1948-1951) were Sundays at 00:00, not
+    Saturdays or Sundays at 02:00.  (Thanks to Takayuki Nikai.)
+
+  Changes to build procedure
+
+    The build procedure now works around mawk 1.3.3's lack of support
+    for character class expressions.  (Problem reported by Ohyama.)
+
+
+Release 2018b - 2018-01-17 23:24:48 -0800
+
+  Briefly:
+  Fix a packaging problem in tz2018a, which was missing 'pacificnew'.
+
+  Changes to build procedure
+
+    The distribution now contains the file 'pacificnew' again.
+    This file was inadvertently omitted in the 2018a distribution.
+    (Problem reported by Matias Fonzo.)
+
+
+Release 2018a - 2018-01-12 22:29:21 -0800
+
+  Briefly:
+  São Tomé and Príncipe switched from +00 to +01.
+  Brazil's DST will now start on November's first Sunday.
+  Ireland's standard time is now in the summer, not the winter.
+  Use Debian-style installation locations, instead of 4.3BSD-style.
+  New zic option -t.
+
+  Changes to past and future timestamps
+
+    São Tomé and Príncipe switched from +00 to +01 on 2018-01-01 at
+    01:00.  (Thanks to Steffen Thorsen and Michael Deckers.)
+
+  Changes to future timestamps
+
+    Starting in 2018 southern Brazil will begin DST on November's
+    first Sunday instead of October's third Sunday.  (Thanks to
+    Steffen Thorsen.)
+
+  Changes to past timestamps
+
+    A discrepancy of 4 s in timestamps before 1931 in South Sudan has
+    been corrected.  The 'backzone' and 'zone.tab' files did not agree
+    with the 'africa' and 'zone1970.tab' files.  (Problem reported by
+    Michael Deckers.)
+
+    The abbreviation invented for Bolivia Summer Time (1931-2) is now
+    BST instead of BOST, to be more consistent with the convention
+    used for Latvian Summer Time (1918-9) and for British Summer Time.
+
+  Changes to tm_isdst
+
+    Change Europe/Dublin so that it observes Irish Standard Time (UT
+    +01) in summer and GMT (as negative daylight-saving) in winter,
+    instead of observing standard time (GMT) in winter and Irish
+    Summer Time (UT +01) in summer.  This change does not affect UT
+    offsets or abbreviations; it affects only whether timestamps are
+    considered to be standard time or daylight-saving time, as
+    expressed in the tm_isdst flag of C's struct tm type.
+    (Discrepancy noted by Derick Rethans.)
+
+  Changes to build procedure
+
+    The default installation locations have been changed to mostly
+    match Debian circa 2017, instead of being designed as an add-on to
+    4.3BSD circa 1986.  This affects the Makefile macros TOPDIR,
+    TZDIR, MANDIR, and LIBDIR.  New Makefile macros TZDEFAULT, USRDIR,
+    USRSHAREDIR, BINDIR, ZDUMPDIR, and ZICDIR let installers tailor
+    locations more precisely.  (This responds to suggestions from
+    Brian Inglis and from Steve Summit.)
+
+    The default installation procedure no longer creates the
+    backward-compatibility link US/Pacific-New, which causes
+    confusion during user setup (e.g., see Debian bug 815200).
+    Use 'make BACKWARD="backward pacificnew"' to create the link
+    anyway, for now.  Eventually we plan to remove the link entirely.
+
+    tzdata.zi now contains a version-number comment.
+    (Suggested by Tom Lane.)
+
+    The Makefile now quotes values like BACKWARD more carefully when
+    passing them to the shell.  (Problem reported by Zefram.)
+
+    Builders no longer need to specify -DHAVE_SNPRINTF on platforms
+    that have snprintf and use pre-C99 compilers.  (Problem reported
+    by Jon Skeet.)
+
+  Changes to code
+
+    zic has a new option -t FILE that specifies the location of the
+    file that determines local time when TZ is unset.  The default for
+    this location can be configured via the new TZDEFAULT makefile
+    macro, which defaults to /etc/localtime.
+
+    Diagnostics and commentary now distinguish UT from UTC more
+    carefully; see theory.html for more information about UT vs UTC.
+
+    zic has been ported to GCC 8's -Wstringop-truncation option.
+    (Problem reported by Martin Sebor.)
+
+  Changes to documentation and commentary
+
+    The zic man page now documents the longstanding behavior that
+    times and years can be out of the usual range, with negative times
+    counting backwards from midnight and with year 0 preceding year 1.
+    (Problem reported by Michael Deckers.)
+
+    The theory.html file now mentions the POSIX limit of six chars
+    per abbreviation, and lists alphabetic abbreviations used.
+
+    The files tz-art.htm and tz-link.htm have been renamed to
+    tz-art.html and tz-link.html, respectively, for consistency with
+    other file names and to simplify web server configuration.
+
+
+Release 2017c - 2017-10-20 14:49:34 -0700
+
+  Briefly:
+  Northern Cyprus switches from +03 to +02/+03 on 2017-10-29.
+  Fiji ends DST 2018-01-14, not 2018-01-21.
+  Namibia switches from +01/+02 to +02 on 2018-04-01.
+  Sudan switches from +03 to +02 on 2017-11-01.
+  Tonga likely switches from +13/+14 to +13 on 2017-11-05.
+  Turks & Caicos switches from -04 to -05/-04 on 2018-11-04.
+  A new file tzdata.zi now holds a small text copy of all data.
+  The zic input format has been regularized slightly.
+
+  Changes to future timestamps
+
+    Northern Cyprus has decided to resume EU rules starting
+    2017-10-29, thus reinstituting winter time.
+
+    Fiji ends DST 2018-01-14 instead of the 2018-01-21 previously
+    predicted.  (Thanks to Dominic Fok.)  Adjust future predictions
+    accordingly.
+
+    Namibia will switch from +01 with DST to +02 all year on
+    2017-09-03 at 02:00.  This affects UT offsets starting 2018-04-01
+    at 02:00.  (Thanks to Steffen Thorsen.)
+
+    Sudan will switch from +03 to +02 on 2017-11-01.  (Thanks to Ahmed
+    Atyya and Yahia Abdalla.)  South Sudan is not switching, so
+    Africa/Juba is no longer a link to Africa/Khartoum.
+
+    Tonga has likely ended its experiment with DST, and will not
+    adjust its clocks on 2017-11-05.  Although Tonga has not announced
+    whether it will continue to observe DST, the IATA is assuming that
+    it will not.  (Thanks to David Wade.)
+
+    Turks & Caicos will switch from -04 all year to -05 with US DST on
+    2018-03-11 at 03:00.  This affects UT offsets starting 2018-11-04
+    at 02:00.  (Thanks to Steffen Thorsen.)
+
+  Changes to past timestamps
+
+    Namibia switched from +02 to +01 on 1994-03-21, not 1994-04-03.
+    (Thanks to Arthur David Olson.)
+
+    Detroit did not observe DST in 1967.
+
+    Use railway time for Asia/Kolkata before 1941, by switching to
+    Madras local time (UT +052110) in 1870, then to IST (UT +0530) in
+    1906.  Also, treat 1941-2's +0630 as DST, like 1942-5.
+
+    Europe/Dublin's 1946 and 1947 fallback transitions occurred at
+    02:00 standard time, not 02:00 DST.  (Thanks to Michael Deckers.)
+
+    Pacific/Apia and Pacific/Pago_Pago switched from Antipodean to
+    American time in 1892, not 1879.  (Thanks to Michael Deckers.)
+
+    Adjust the 1867 transition in Alaska to better reflect the
+    historical record, by changing it to occur on 1867-10-18 at 15:30
+    Sitka time rather than at the start of 1867-10-17 local time.
+    Although strictly speaking this is accurate only for Sitka,
+    the rest of Alaska's blanks need to be filled in somehow.
+
+    Fix off-by-one errors in UT offsets for Adak and Nome before 1867.
+    (Thanks to Michael Deckers.)
+
+    Add 7 s to the UT offset in Asia/Yangon before 1920.
+
+  Changes to zone names
+
+    Remove Canada/East-Saskatchewan from the 'backward' file, as it
+    exceeded the 14-character limit and was an unused misnomer anyway.
+
+  Changes to build procedure
+
+    To support applications that prefer to read time zone data in text
+    form, two zic input files tzdata.zi and leapseconds are now
+    installed by default.  The commands 'zic tzdata.zi' and 'zic -L
+    leapseconds tzdata.zi' can reproduce the tzdata binary files
+    without and with leap seconds, respectively.  To prevent these two
+    new files from being installed, use 'make TZDATA_TEXT=', and to
+    suppress leap seconds from the tzdata text installation, use 'make
+    TZDATA_TEXT=tzdata.zi'.
+
+    'make BACKWARD=' now suppresses backward-compatibility names
+    like 'US/Pacific' that are defined in the 'backward' and
+    'pacificnew' files.
+
+    'make check' now works on systems that lack a UTF-8 locale,
+    or that lack the nsgmls program.  Set UTF8_LOCALE to configure
+    the name of a UTF-8 locale, if you have one.
+
+    Y2K runtime checks are no longer enabled by default.  Add
+    -DDEPRECATE_TWO_DIGIT_YEARS to CFLAGS to enable them, instead of
+    adding -DNO_RUN_TIME_WARNINGS_ABOUT_YEAR_2000_PROBLEMS_THANK_YOU
+    to disable them.  (New name suggested by Brian Inglis.)
+
+    The build procedure for zdump now works on AIX 7.1.
+    (Problem reported by Kees Dekker.)
+
+  Changes to code
+
+    zic and the reference runtime now reject multiple leap seconds
+    within 28 days of each other, or leap seconds before the Epoch.
+    As a result, support for double leap seconds, which was
+    obsolescent and undocumented, has been removed.  Double leap
+    seconds were an error in the C89 standard; they have never existed
+    in civil timekeeping.  (Thanks to Robert Elz and Bradley White for
+    noticing glitches in the code that uncovered this problem.)
+
+    zic now warns about use of the obsolescent and undocumented -y
+    option, and about use of the obsolescent TYPE field of Rule lines.
+
+    zic now allows unambiguous abbreviations like "Sa" and "Su" for
+    weekdays; formerly it rejected them due to a bug.  Conversely, zic
+    no longer considers non-prefixes to be abbreviations; for example,
+    it no longer accepts "lF" as an abbreviation for "lastFriday".
+    Also, zic warns about the undocumented usage with a "last-"
+    prefix, e.g., "last-Fri".
+
+    Similarly, zic now accepts the unambiguous abbreviation "L" for
+    "Link" in ordinary context and for "Leap" in leap-second context.
+    Conversely, zic no longer accepts non-prefixes such as "La" as
+    abbreviations for words like "Leap".
+
+    zic no longer accepts leap second lines in ordinary input, or
+    ordinary lines in leap second input.  Formerly, zic sometimes
+    warned about this undocumented usage and handled it incorrectly.
+
+    The new macro HAVE_TZNAME governs whether the tzname external
+    variable is exported, instead of USG_COMPAT.  USG_COMPAT now
+    governs only the external variables "timezone" and "daylight".
+    This change is needed because the three variables are not in the
+    same category: although POSIX requires tzname, it specifies the
+    other two variables as optional.  Also, USG_COMPAT is now 1 or 0:
+    if not defined, the code attempts to guess it from other macros.
+
+    localtime.c and difftime.c no longer require stdio.h, and .c files
+    other than zic.c no longer require sys/wait.h.
+
+    zdump.c no longer assumes snprintf.  (Reported by Jonathan Leffler.)
+
+    Calculation of time_t extrema works around a bug in GCC 4.8.4
+    (Reported by Stan Shebs and Joseph Myers.)
+
+    zic.c no longer mistranslates formats of line numbers in non-English
+    locales.  (Problem reported by Benno Schulenberg.)
+
+    Several minor changes have been made to the code to make it a
+    bit easier to port to MS-Windows and Solaris.  (Thanks to Kees
+    Dekker for reporting the problems.)
+
+  Changes to documentation and commentary
+
+    The two new files 'theory.html' and 'calendars' contain the
+    contents of the removed file 'Theory'.  The goal is to document
+    tzdb theory more accessibly.
+
+    The zic man page now documents abbreviation rules.
+
+    tz-link.htm now covers how to apply tzdata changes to clients.
+    (Thanks to Jorge Fábregas for the AIX link.)  It also mentions MySQL.
+
+    The leap-seconds.list URL has been updated to something that is
+    more reliable for tzdb.  (Thanks to Tim Parenti and Brian Inglis.)
+
+Release 2017b - 2017-03-17 07:30:38 -0700
+
+  Briefly: Haiti has resumed DST.
+
+  Changes to past and future timestamps
+
+    Haiti resumed observance of DST in 2017.  (Thanks to Steffen Thorsen.)
+
+  Changes to past timestamps
+
+    Liberia changed from -004430 to +00 on 1972-01-07, not 1972-05-01.
+
+    Use "MMT" to abbreviate Liberia's time zone before 1972, as "-004430"
+    is one byte over the POSIX limit.  (Problem reported by Derick Rethans.)
+
+  Changes to code
+
+    The reference localtime implementation now falls back on the
+    current US daylight-saving transition rules rather than the
+    1987-2006 rules.  This fallback occurs only when (1) the TZ
+    environment variable has a value like "AST4ADT" that asks
+    for daylight saving time but does not specify the rules, (2) there
+    is no file by that name, and (3) the TZDEFRULES file cannot be
+    loaded.  (Thanks to Tom Lane.)
+
+
+Release 2017a - 2017-02-28 00:05:36 -0800
+
+  Briefly: Southern Chile moves from -04/-03 to -03, and Mongolia
+  discontinues DST.
+
+  Changes to future timestamps
+
+    Mongolia no longer observes DST.  (Thanks to Ganbold Tsagaankhuu.)
+
+    Chile's Region of Magallanes moves from -04/-03 to -03 year-round.
+    Its clocks diverge from America/Santiago starting 2017-05-13 at
+    23:00, hiving off a new zone America/Punta_Arenas.  Although the
+    Chilean government says this change expires in May 2019, for now
+    assume it's permanent.  (Thanks to Juan Correa and Deborah
+    Goldsmith.)  This also affects Antarctica/Palmer.
+
+  Changes to past timestamps
+
+    Fix many entries for historical timestamps for Europe/Madrid
+    before 1979, to agree with tables compiled by Pere Planesas of the
+    National Astronomical Observatory of Spain.  As a side effect,
+    this changes some timestamps for Africa/Ceuta before 1929, which
+    are probably guesswork anyway.  (Thanks to Steve Allen and
+    Pierpaolo Bernardi for the heads-ups, and to Michael Deckers for
+    correcting the 1901 transition.)
+
+    Ecuador observed DST from 1992-11-28 to 1993-02-05.
+    (Thanks to Alois Treindl.)
+
+    Asia/Atyrau and Asia/Oral were at +03 (not +04) before 1930-06-21.
+    (Thanks to Stepan Golosunov.)
+
+  Changes to past and future time zone abbreviations
+
+    Switch to numeric time zone abbreviations for South America, as
+    part of the ongoing project of removing invented abbreviations.
+    This avoids the need to invent an abbreviation for the new Chilean
+    new zone.  Similarly, switch from invented to numeric time zone
+    abbreviations for Afghanistan, American Samoa, the Azores,
+    Bangladesh, Bhutan, the British Indian Ocean Territory, Brunei,
+    Cape Verde, Chatham Is, Christmas I, Cocos (Keeling) Is, Cook Is,
+    Dubai, East Timor, Eucla, Fiji, French Polynesia, Greenland,
+    Indochina, Iran, Iraq, Kiribati, Lord Howe, Macquarie, Malaysia,
+    the Maldives, Marshall Is, Mauritius, Micronesia, Mongolia,
+    Myanmar, Nauru, Nepal, New Caledonia, Niue, Norfolk I, Palau,
+    Papua New Guinea, the Philippines, Pitcairn, Qatar, Réunion, St
+    Pierre & Miquelon, Samoa, Saudi Arabia, Seychelles, Singapore,
+    Solomon Is, Tokelau, Tuvalu, Wake, Vanuatu, Wallis & Futuna, and
+    Xinjiang; for 20-minute daylight saving time in Ghana before 1943;
+    for half-hour daylight saving time in Belize before 1944 and in
+    the Dominican Republic before 1975; and for Canary Islands before
+    1946, for Guinea-Bissau before 1975, for Iceland before 1969, for
+    Indian Summer Time before 1942, for Indonesia before around 1964,
+    for Kenya before 1960, for Liberia before 1973, for Madeira before
+    1967, for Namibia before 1943, for the Netherlands in 1937-9, for
+    Pakistan before 1971, for Western Sahara before 1977, and for
+    Zaporozhye in 1880-1924.
+
+    For Alaska time from 1900 through 1967, instead of "CAT" use the
+    abbreviation "AST", the abbreviation commonly used at the time
+    (Atlantic Standard Time had not been standardized yet).  Use "AWT"
+    and "APT" instead of the invented abbreviations "CAWT" and "CAPT".
+
+    Use "CST" and "CDT" instead of invented abbreviations for Macau
+    before 1999 and Taiwan before 1938, and use "JST" instead of the
+    invented abbreviation "JCST" for Japan and Korea before 1938.
+
+  Change to database entry category
+
+    Move the Pacific/Johnston link from 'australasia' to 'backward',
+    since Johnston is now uninhabited.
+
+  Changes to code
+
+    zic no longer mishandles some transitions in January 2038 when it
+    attempts to work around Qt bug 53071.  This fixes a bug affecting
+    Pacific/Tongatapu that was introduced in zic 2016e.  localtime.c
+    now contains a workaround, useful when loading a file generated by
+    a buggy zic.  (Problem and localtime.c fix reported by Bradley
+    White.)
+
+    zdump -i now outputs non-hour numeric time zone abbreviations
+    without a colon, e.g., "+0530" rather than "+05:30".  This agrees
+    with zic %z and with common practice, and simplifies auditing of
+    zdump output.
+
+    zdump is now buildable again with -DUSE_LTZ=0.
+    (Problem reported by Joseph Myers.)
+
+    zdump.c now always includes private.h, to avoid code duplication
+    with private.h.  (Problem reported by Kees Dekker.)
+
+    localtime.c no longer mishandles early or late timestamps
+    when TZ is set to a POSIX-style string that specifies DST.
+    (Problem reported by Kees Dekker.)
+
+    date and strftime now cause %z to generate "-0000" instead of
+    "+0000" when the UT offset is zero and the time zone abbreviation
+    begins with "-".
+
+  Changes to documentation and commentary
+
+    The 'Theory' file now better documents choice of historical time
+    zone abbreviations.  (Problems reported by Michael Deckers.)
+
+    tz-link.htm now covers leap smearing, which is popular in clouds.
+
+
+Release 2016j - 2016-11-22 23:17:13 -0800
+
+  Briefly: Saratov, Russia moves from +03 to +04 on 2016-12-04.
+
+  Changes to future timestamps
+
+    Saratov, Russia switches from +03 to +04 on 2016-12-04 at 02:00.
+    This hives off a new zone Europe/Saratov from Europe/Volgograd.
+    (Thanks to Yuri Konotopov and Stepan Golosunov.)
+
+  Changes to past timestamps
+
+    The new zone Asia/Atyrau for Atyraū Region, Kazakhstan, is like
+    Asia/Aqtau except it switched from +05/+06 to +04/+05 in spring
+    1999, not fall 1994.  (Thanks to Stepan Golosunov.)
+
+  Changes to past time zone abbreviations
+
+    Asia/Gaza and Asia/Hebron now use "EEST", not "EET", to denote
+    summer time before 1948.  The old use of "EET" was a typo.
+
+  Changes to code
+
+    zic no longer mishandles file systems that lack hard links, fixing
+    bugs introduced in 2016g.  (Problems reported by Tom Lane.)
+    Also, when the destination already contains symbolic links, zic
+    should now work better on systems where the 'link' system call
+    does not follow symbolic links.
+
+  Changes to documentation and commentary
+
+    tz-link.htm now documents the relationship between release version
+    numbers and development-repository commit tags.  (Suggested by
+    Paul Koning.)
+
+    The 'Theory' file now documents UT.
+
+    iso3166.tab now accents "Curaçao", and commentary now mentions
+    the names "Cabo Verde" and "Czechia".  (Thanks to Jiří Boháč.)
+
+
+Release 2016i - 2016-11-01 23:19:52 -0700
+
+  Briefly: Cyprus split into two time zones on 2016-10-30, and Tonga
+  reintroduces DST on 2016-11-06.
+
+  Changes to future timestamps
+
+    Pacific/Tongatapu begins DST on 2016-11-06 at 02:00, ending on
+    2017-01-15 at 03:00.  Assume future observances in Tonga will be
+    from the first Sunday in November through the third Sunday in
+    January, like Fiji.  (Thanks to Pulu ʻAnau.)  Switch to numeric
+    time zone abbreviations for this zone.
+
+  Changes to past and future timestamps
+
+    Northern Cyprus is now +03 year round, causing a split in Cyprus
+    time zones starting 2016-10-30 at 04:00.  This creates a zone
+    Asia/Famagusta.  (Thanks to Even Scharning and Matt Johnson.)
+
+    Antarctica/Casey switched from +08 to +11 on 2016-10-22.
+    (Thanks to Steffen Thorsen.)
+
+  Changes to past timestamps
+
+    Several corrections were made for pre-1975 timestamps in Italy.
+    These affect Europe/Malta, Europe/Rome, Europe/San_Marino, and
+    Europe/Vatican.
+
+    First, the 1893-11-01 00:00 transition in Italy used the new UT
+    offset (+01), not the old (+00:49:56).  (Thanks to Michael
+    Deckers.)
+
+    Second, rules for daylight saving in Italy were changed to agree
+    with Italy's National Institute of Metrological Research (INRiM)
+    except for 1944, as follows (thanks to Pierpaolo Bernardi, Brian
+    Inglis, and Michael Deckers):
+
+      The 1916-06-03 transition was at 24:00, not 00:00.
+
+      The 1916-10-01, 1919-10-05, and 1920-09-19 transitions were at
+      00:00, not 01:00.
+
+      The 1917-09-30 and 1918-10-06 transitions were at 24:00, not
+      01:00.
+
+      The 1944-09-17 transition was at 03:00, not 01:00.  This
+      particular change is taken from Italian law as INRiM's table,
+      (which says 02:00) appears to have a typo here.  Also, keep the
+      1944-04-03 transition for Europe/Rome, as Rome was controlled by
+      Germany then.
+
+      The 1967-1970 and 1972-1974 fallback transitions were at 01:00,
+      not 00:00.
+
+  Changes to code
+
+    The code should now be buildable on AmigaOS merely by setting the
+    appropriate Makefile variables.  (From a patch by Carsten Larsen.)
+
+
+Release 2016h - 2016-10-19 23:17:57 -0700
+
+  Changes to future timestamps
+
+    Asia/Gaza and Asia/Hebron end DST on 2016-10-29 at 01:00, not
+    2016-10-21 at 00:00.  (Thanks to Sharef Mustafa.)  Predict that
+    future fall transitions will be on the last Saturday of October
+    at 01:00, which is consistent with predicted spring transitions
+    on the last Saturday of March.  (Thanks to Tim Parenti.)
+
+  Changes to past timestamps
+
+    In Turkey, transitions in 1986-1990 were at 01:00 standard time
+    not at 02:00, and the spring 1994 transition was on March 20, not
+    March 27.  (Thanks to Kıvanç Yazan.)
+
+  Changes to past and future time zone abbreviations
+
+    Asia/Colombo now uses numeric time zone abbreviations like "+0530"
+    instead of alphabetic ones like "IST" and "LKT".  Various
+    English-language sources use "IST", "LKT" and "SLST", with no
+    working consensus.  (Usage of "SLST" mentioned by Sadika
+    Sumanapala.)
+
+  Changes to code
+
+    zic no longer mishandles relativizing file names when creating
+    symbolic links like /etc/localtime, when these symbolic links
+    are outside the usual directory hierarchy.  This fixes a bug
+    introduced in 2016g.  (Problem reported by Andreas Stieger.)
+
+  Changes to build procedure
+
+    New rules 'traditional_tarballs' and 'traditional_signatures' for
+    building just the traditional-format distribution.  (Requested by
+    Deborah Goldsmith.)
+
+    The file 'version' is now put into the tzdata tarball too.
+    (Requested by Howard Hinnant.)
+
+  Changes to documentation and commentary
+
+    The 'Theory' file now has a section on interface stability.
+    (Requested by Paul Koning.)  It also mentions features like
+    tm_zone and localtime_rz that have long been supported by the
+    reference code.
+
+    tz-link.htm has improved coverage of time zone boundaries suitable
+    for geolocation.  (Thanks to heads-ups from Evan Siroky and Matt
+    Johnson.)
+
+    The US commentary now mentions Allen and the "day of two noons".
+
+    The Fiji commentary mentions the government's 2016-10-03 press
+    release.  (Thanks to Raymond Kumar.)
+
+
+Release 2016g - 2016-09-13 08:56:38 -0700
+
+  Changes to future timestamps
+
+    Turkey switched from EET/EEST (+02/+03) to permanent +03,
+    effective 2016-09-07.  (Thanks to Burak AYDIN.)  Use "+03" rather
+    than an invented abbreviation for the new time.
+
+    New leap second 2016-12-31 23:59:60 UTC as per IERS Bulletin C 52.
+    (Thanks to Tim Parenti.)
+
+  Changes to past timestamps
+
+    For America/Los_Angeles, spring-forward transition times have been
+    corrected from 02:00 to 02:01 in 1948, and from 02:00 to 01:00 in
+    1950-1966.
+
+    For zones using Soviet time on 1919-07-01, transitions to UT-based
+    time were at 00:00 UT, not at 02:00 local time.  The affected
+    zones are Europe/Kirov, Europe/Moscow, Europe/Samara, and
+    Europe/Ulyanovsk.  (Thanks to Alexander Belopolsky.)
+
+  Changes to past and future time zone abbreviations
+
+    The Factory zone now uses the time zone abbreviation -00 instead
+    of a long English-language string, as -00 is now the normal way to
+    represent an undefined time zone.
+
+    Several zones in Antarctica and the former Soviet Union, along
+    with zones intended for ships at sea that cannot use POSIX TZ
+    strings, now use numeric time zone abbreviations instead of
+    invented or obsolete alphanumeric abbreviations.  The affected
+    zones are Antarctica/Casey, Antarctica/Davis,
+    Antarctica/DumontDUrville, Antarctica/Mawson, Antarctica/Rothera,
+    Antarctica/Syowa, Antarctica/Troll, Antarctica/Vostok,
+    Asia/Anadyr, Asia/Ashgabat, Asia/Baku, Asia/Bishkek, Asia/Chita,
+    Asia/Dushanbe, Asia/Irkutsk, Asia/Kamchatka, Asia/Khandyga,
+    Asia/Krasnoyarsk, Asia/Magadan, Asia/Omsk, Asia/Sakhalin,
+    Asia/Samarkand, Asia/Srednekolymsk, Asia/Tashkent, Asia/Tbilisi,
+    Asia/Ust-Nera, Asia/Vladivostok, Asia/Yakutsk, Asia/Yekaterinburg,
+    Asia/Yerevan, Etc/GMT-14, Etc/GMT-13, Etc/GMT-12, Etc/GMT-11,
+    Etc/GMT-10, Etc/GMT-9, Etc/GMT-8, Etc/GMT-7, Etc/GMT-6, Etc/GMT-5,
+    Etc/GMT-4, Etc/GMT-3, Etc/GMT-2, Etc/GMT-1, Etc/GMT+1, Etc/GMT+2,
+    Etc/GMT+3, Etc/GMT+4, Etc/GMT+5, Etc/GMT+6, Etc/GMT+7, Etc/GMT+8,
+    Etc/GMT+9, Etc/GMT+10, Etc/GMT+11, Etc/GMT+12, Europe/Kaliningrad,
+    Europe/Minsk, Europe/Samara, Europe/Volgograd, and
+    Indian/Kerguelen.  For Europe/Moscow the invented abbreviation MSM
+    was replaced by +05, whereas MSK and MSD were kept as they are not
+    our invention and are widely used.
+
+  Changes to zone names
+
+    Rename Asia/Rangoon to Asia/Yangon, with a backward compatibility link.
+    (Thanks to David Massoud.)
+
+  Changes to code
+
+    zic no longer generates binary files containing POSIX TZ-like
+    strings that disagree with the local time type after the last
+    explicit transition in the data.  This fixes a bug with
+    Africa/Casablanca and Africa/El_Aaiun in some year-2037 timestamps
+    on the reference platform.  (Thanks to Alexander Belopolsky for
+    reporting the bug and suggesting a way forward.)
+
+    If the installed localtime and/or posixrules files are symbolic
+    links, zic now keeps them symbolic links when updating them, for
+    compatibility with platforms like OpenSUSE where other programs
+    configure these files as symlinks.
+
+    zic now avoids hard linking to symbolic links, avoids some
+    unnecessary mkdir and stat system calls, and uses shorter file
+    names internally.
+
+    zdump has a new -i option to generate transitions in a
+    more-compact but still human-readable format.  This option is
+    experimental, and the output format may change in future versions.
+    (Thanks to Jon Skeet for suggesting that an option was needed,
+    and thanks to Tim Parenti and Chris Rovick for further comments.)
+
+  Changes to build procedure
+
+    An experimental distribution format is available, in addition
+    to the traditional format which will continue to be distributed.
+    The new format is a tarball tzdb-VERSION.tar.lz with signature
+    file tzdb-VERSION.tar.lz.asc.  It unpacks to a top-level directory
+    tzdb-VERSION containing the code and data of the traditional
+    two-tarball format, along with extra data that may be useful.
+    (Thanks to Antonio Diaz Diaz, Oscar van Vlijmen, and many others
+    for comments about the experimental format.)
+
+    The release version number is now more accurate in the usual case
+    where releases are built from a Git repository.  For example, if
+    23 commits and some working-file changes have been made since
+    release 2016g, the version number is now something like
+    '2016g-23-g50556e3-dirty' instead of the misleading '2016g'.
+    Tagged releases use the same version number format as before,
+    e.g., '2016g'.  To support the more-accurate version number, its
+    specification has moved from a line in the Makefile to a new
+    source file 'version'.
+
+    The experimental distribution contains a file to2050.tzs that
+    contains what should be the output of 'zdump -i -c 2050' on
+    primary zones.  If this file is available, 'make check' now checks
+    that zdump generates this output.
+
+    'make check_web' now works on Fedora-like distributions.
+
+  Changes to documentation and commentary
+
+    tzfile.5 now documents the new restriction on POSIX TZ-like
+    strings that is now implemented by zic.
+
+    Comments now cite URLs for some 1917-1921 Russian DST decrees.
+    (Thanks to Alexander Belopolsky.)
+
+    tz-link.htm mentions JuliaTime (thanks to Curtis Vogt) and Time4J
+    (thanks to Meno Hochschild) and ThreeTen-Extra, and its
+    description of Java 8 has been brought up to date (thanks to
+    Stephen Colebourne).  Its description of local time on Mars has
+    been updated to match current practice, and URLs have been updated
+    and some obsolete ones removed.
+
+
+Release 2016f - 2016-07-05 16:26:51 +0200
+
+  Changes affecting future timestamps
+
+    The Egyptian government changed its mind on short notice, and
+    Africa/Cairo will not introduce DST starting 2016-07-07 after all.
+    (Thanks to Mina Samuel.)
+
+    Asia/Novosibirsk switches from +06 to +07 on 2016-07-24 at 02:00.
+    (Thanks to Stepan Golosunov.)
+
+  Changes to past and future timestamps
+
+    Asia/Novokuznetsk and Asia/Novosibirsk now use numeric time zone
+    abbreviations instead of invented ones.
+
+  Changes affecting past timestamps
+
+    Europe/Minsk's 1992-03-29 spring-forward transition was at 02:00 not 00:00.
+    (Thanks to Stepan Golosunov.)
+
+
+Release 2016e - 2016-06-14 08:46:16 -0700
+
+  Changes affecting future timestamps
+
+    Africa/Cairo observes DST in 2016 from July 7 to the end of October.
+    Guess October 27 and 24:00 transitions.  (Thanks to Steffen Thorsen.)
+    For future years, guess April's last Thursday to October's last
+    Thursday except for Ramadan.
+
+  Changes affecting past timestamps
+
+    Locations while uninhabited now use '-00', not 'zzz', as a
+    placeholder time zone abbreviation.  This is inspired by Internet
+    RFC 3339 and is more consistent with numeric time zone
+    abbreviations already used elsewhere.  The change affects several
+    arctic and antarctic locations, e.g., America/Cambridge_Bay before
+    1920 and Antarctica/Troll before 2005.
+
+    Asia/Baku's 1992-09-27 transition from +04 (DST) to +04 (non-DST) was
+    at 03:00, not 23:00 the previous day.  (Thanks to Michael Deckers.)
+
+  Changes to code
+
+    zic now outputs a dummy transition at time 2**31 - 1 in zones
+    whose POSIX-style TZ strings contain a '<'.  This mostly works
+    around Qt bug 53071 <https://bugreports.qt.io/browse/QTBUG-53071>.
+    (Thanks to Zhanibek Adilbekov for reporting the Qt bug.)
+
+  Changes affecting documentation and commentary
+
+    tz-link.htm says why governments should give plenty of notice for
+    time zone or DST changes, and refers to Matt Johnson's blog post.
+
+    tz-link.htm mentions Tzdata for Elixir.  (Thanks to Matt Johnson.)
+
+
+Release 2016d - 2016-04-17 22:50:29 -0700
+
+  Changes affecting future timestamps
+
+    America/Caracas switches from -0430 to -04 on 2016-05-01 at 02:30.
+    (Thanks to Alexander Krivenyshev for the heads-up.)
+
+    Asia/Magadan switches from +10 to +11 on 2016-04-24 at 02:00.
+    (Thanks to Alexander Krivenyshev and Matt Johnson.)
+
+    New zone Asia/Tomsk, split off from Asia/Novosibirsk.  It covers
+    Tomsk Oblast, Russia, which switches from +06 to +07 on 2016-05-29
+    at 02:00.  (Thanks to Stepan Golosunov.)
+
+  Changes affecting past timestamps
+
+    New zone Europe/Kirov, split off from Europe/Volgograd.  It covers
+    Kirov Oblast, Russia, which switched from +04/+05 to +03/+04 on
+    1989-03-26 at 02:00, roughly a year after Europe/Volgograd made
+    the same change.  (Thanks to Stepan Golosunov.)
+
+    Russia and nearby locations had daylight-saving transitions on
+    1992-03-29 at 02:00 and 1992-09-27 at 03:00, instead of on
+    1992-03-28 at 23:00 and 1992-09-26 at 23:00.  (Thanks to Stepan
+    Golosunov.)
+
+    Many corrections to historical time in Kazakhstan from 1991
+    through 2005.  (Thanks to Stepan Golosunov.)  Replace Kazakhstan's
+    invented time zone abbreviations with numeric abbreviations.
+
+  Changes to commentary
+
+    Mention Internet RFCs 7808 (TZDIST) and 7809 (CalDAV time zone references).
+
+
+Release 2016c - 2016-03-23 00:51:27 -0700
+
+  Changes affecting future timestamps
+
+    Azerbaijan no longer observes DST.  (Thanks to Steffen Thorsen.)
+
+    Chile reverts from permanent to seasonal DST.  (Thanks to Juan
+    Correa for the heads-up, and to Tim Parenti for corrections.)
+    Guess that future transitions are August's and May's second
+    Saturdays at 24:00 mainland time.  Also, call the period from
+    2014-09-07 through 2016-05-14 daylight saving time instead of
+    standard time, as that seems more appropriate now.
+
+  Changes affecting past timestamps
+
+    Europe/Kaliningrad and Europe/Vilnius changed from +03/+04 to
+    +02/+03 on 1989-03-26, not 1991-03-31.  Europe/Volgograd changed
+    from +04/+05 to +03/+04 on 1988-03-27, not 1989-03-26.
+    (Thanks to Stepan Golosunov.)
+
+  Changes to commentary
+
+    Several updates and URLs for historical and proposed Russian changes.
+    (Thanks to Stepan Golosunov, Matt Johnson, and Alexander Krivenyshev.)
+
+
+Release 2016b - 2016-03-12 17:30:14 -0800
+
+  Compatibility note
+
+    Starting with release 2016b, some data entries cause zic implementations
+    derived from tz releases 2005j through 2015e to issue warnings like
+    "time zone abbreviation differs from POSIX standard (+03)".
+    These warnings should not otherwise affect zic's output and can safely be
+    ignored on today's platforms, as the warnings refer to a restriction in
+    POSIX.1-1988 that was removed in POSIX.1-2001.  One way to suppress the
+    warnings is to upgrade to zic derived from tz releases 2015f and later.
+
+  Changes affecting future timestamps
+
+    New zones Europe/Astrakhan and Europe/Ulyanovsk for Astrakhan and
+    Ulyanovsk Oblasts, Russia, both of which will switch from +03 to +04 on
+    2016-03-27 at 02:00 local time.  They need distinct zones since their
+    post-1970 histories disagree.  New zone Asia/Barnaul for Altai Krai and
+    Altai Republic, Russia, which will switch from +06 to +07 on the same date
+    and local time.  The Astrakhan change is already official; the others have
+    passed the first reading in the State Duma and are extremely likely.
+    Also, Asia/Sakhalin moves from +10 to +11 on 2016-03-27 at 02:00.
+    (Thanks to Alexander Krivenyshev for the heads-up, and to Matt Johnson
+    and Stepan Golosunov for followup.)
+
+    As a trial of a new system that needs less information to be made up,
+    the new zones use numeric time zone abbreviations like "+04"
+    instead of invented abbreviations like "ASTT".
+
+    Haiti will not observe DST in 2016.  (Thanks to Jean Antoine via
+    Steffen Thorsen.)
+
+    Palestine's spring-forward transition on 2016-03-26 is at 01:00, not 00:00.
+    (Thanks to Hannah Kreitem.) Guess future transitions will be March's last
+    Saturday at 01:00, not March's last Friday at 24:00.
+
+  Changes affecting past timestamps
+
+    Europe/Chisinau observed DST during 1990, and switched from +04 to
+    +03 at 1990-05-06 02:00, instead of switching from +03 to +02.
+    (Thanks to Stepan Golosunov.)
+
+    1991 abbreviations in Europe/Samara should be SAMT/SAMST, not
+    KUYT/KUYST.  (Thanks to Stepan Golosunov.)
+
+  Changes to code
+
+    tzselect's diagnostics and checking, and checktab.awk's checking,
+    have been improved.  (Thanks to J William Piggott.)
+
+    tzcode now builds under MinGW.  (Thanks to Ian Abbott and Esben Haabendal.)
+
+    tzselect now tests Julian-date TZ settings more accurately.
+    (Thanks to J William Piggott.)
+
+  Changes to commentary
+
+    Comments in zone tables have been improved.  (Thanks to J William Piggott.)
+
+    tzselect again limits its menu comments so that menus fit on a
+    24×80 alphanumeric display.
+
+    A new web page tz-how-to.html.  (Thanks to Bill Seymour.)
+
+    In the Theory file, the description of possible time zone abbreviations in
+    tzdata has been cleaned up, as the old description was unclear and
+    inconsistent.  (Thanks to Alain Mouette for reporting the problem.)
+
+
+Release 2016a - 2016-01-26 23:28:02 -0800
+
+  Changes affecting future timestamps
+
+    America/Cayman will not observe daylight saving this year after all.
+    Revert our guess that it would.  (Thanks to Matt Johnson.)
+
+    Asia/Chita switches from +0800 to +0900 on 2016-03-27 at 02:00.
+    (Thanks to Alexander Krivenyshev.)
+
+    Asia/Tehran now has DST predictions for the year 2038 and later,
+    to be March 21 00:00 to September 21 00:00.  This is likely better
+    than predicting no DST, albeit off by a day every now and then.
+
+  Changes affecting past and future timestamps
+
+    America/Metlakatla switched from PST all year to AKST/AKDT on
+    2015-11-01 at 02:00.  (Thanks to Steffen Thorsen.)
+
+    America/Santa_Isabel has been removed, and replaced with a
+    backward compatibility link to America/Tijuana.  Its contents were
+    apparently based on a misreading of Mexican legislation.
+
+  Changes affecting past timestamps
+
+    Asia/Karachi's two transition times in 2002 were off by a minute.
+    (Thanks to Matt Johnson.)
+
+  Changes affecting build procedure
+
+    An installer can now combine leap seconds with use of the backzone file,
+    e.g., with 'make PACKRATDATA=backzone REDO=posix_right zones'.
+    The old 'make posix_packrat' rule is now marked as obsolescent.
+    (Thanks to Ian Abbott for an initial implementation.)
+
+  Changes affecting documentation and commentary
+
+    A new file LICENSE makes it easier to see that the code and data
+    are mostly public-domain.  (Thanks to James Knight.)  The three
+    non-public-domain files now use the current (3-clause) BSD license
+    instead of older versions of that license.
+
+    tz-link.htm mentions the BDE library (thanks to Andrew Paprocki),
+    CCTZ (thanks to Tim Parenti), TimeJones.com, and has a new section
+    on editing tz source files (with a mention of Sublime zoneinfo,
+    thanks to Gilmore Davidson).
+
+    The Theory and asia files now mention the 2015 book "The Global
+    Transformation of Time, 1870-1950", and cite a couple of reviews.
+
+    The America/Chicago entry now documents the informal use of US
+    central time in Fort Pierre, South Dakota.  (Thanks to Rick
+    McDermid, Matt Johnson, and Steve Jones.)
+
+
+Release 2015g - 2015-10-01 00:39:51 -0700
+
+  Changes affecting future timestamps
+
+    Turkey's 2015 fall-back transition is scheduled for Nov. 8, not Oct. 25.
+    (Thanks to Fatih.)
+
+    Norfolk moves from +1130 to +1100 on 2015-10-04 at 02:00 local time.
+    (Thanks to Alexander Krivenyshev.)
+
+    Fiji's 2016 fall-back transition is scheduled for January 17, not 24.
+    (Thanks to Ken Rylander.)
+
+    Fort Nelson, British Columbia will not fall back on 2015-11-01.  It has
+    effectively been on MST (-0700) since it advanced its clocks on 2015-03-08.
+    New zone America/Fort_Nelson.  (Thanks to Matt Johnson.)
+
+  Changes affecting past timestamps
+
+    Norfolk observed DST from 1974-10-27 02:00 to 1975-03-02 02:00.
+
+  Changes affecting code
+
+    localtime no longer mishandles America/Anchorage after 2037.
+    (Thanks to Bradley White for reporting the bug.)
+
+    On hosts with signed 32-bit time_t, localtime no longer mishandles
+    Pacific/Fiji after 2038-01-16 14:00 UTC.
+
+    The localtime module allows the variables 'timezone', 'daylight',
+    and 'altzone' to be in common storage shared with other modules,
+    and declares them in case the system <time.h> does not.
+    (Problems reported by Kees Dekker.)
+
+    On platforms with tm_zone, strftime.c now assumes it is not NULL.
+    This simplifies the code and is consistent with zdump.c.
+    (Problem reported by Christos Zoulas.)
+
+  Changes affecting documentation
+
+   The tzfile man page now documents that transition times denote the
+   starts (not the ends) of the corresponding time periods.
+   (Ambiguity reported by Bill Seymour.)
+
+
+Release 2015f - 2015-08-10 18:06:56 -0700
+
+  Changes affecting future timestamps
+
+    North Korea switches to +0830 on 2015-08-15.  (Thanks to Steffen Thorsen.)
+    The abbreviation remains "KST".  (Thanks to Robert Elz.)
+
+    Uruguay no longer observes DST.  (Thanks to Steffen Thorsen
+    and Pablo Camargo.)
+
+  Changes affecting past and future timestamps
+
+    Moldova starts and ends DST at 00:00 UTC, not at 01:00 UTC.
+    (Thanks to Roman Tudos.)
+
+  Changes affecting data format and code
+
+    zic's '-y YEARISTYPE' option is no longer documented.  The TYPE
+    field of a Rule line should now be '-'; the old values 'even',
+    'odd', 'uspres', 'nonpres', 'nonuspres' were already undocumented.
+    Although the implementation has not changed, these features do not
+    work in the default installation, they are not used in the data,
+    and they are now considered obsolescent.
+
+    zic now checks that two rules don't take effect at the same time.
+    (Thanks to Jon Skeet and Arthur David Olson.)  Constraints on
+    simultaneity are now documented.
+
+    The two characters '%z' in a zone format now stand for the UT
+    offset, e.g., '-07' for seven hours behind UT and '+0530' for
+    five hours and thirty minutes ahead.  This better supports time
+    zone abbreviations conforming to POSIX.1-2001 and later.
+
+  Changes affecting installed data files
+
+    Comments for America/Halifax and America/Glace_Bay have been improved.
+    (Thanks to Brian Inglis.)
+
+    Data entries have been simplified for Atlantic/Canary, Europe/Simferopol,
+    Europe/Sofia, and Europe/Tallinn.  This yields slightly smaller
+    installed data files for Europe/Simferopol and Europe/Tallinn.
+    It does not affect timestamps.  (Thanks to Howard Hinnant.)
+
+  Changes affecting code
+
+    zdump and zic no longer warn about valid time zone abbreviations
+    like '-05'.
+
+    Some Visual Studio 2013 warnings have been suppressed.
+    (Thanks to Kees Dekker.)
+
+    'date' no longer sets the time of day and its -a, -d, -n and -t
+    options have been removed.  Long obsolescent, the implementation
+    of these features had porting problems.  Builders no longer need
+    to configure HAVE_ADJTIME, HAVE_SETTIMEOFDAY, or HAVE_UTMPX_H.
+    (Thanks to Kees Dekker for pointing out the problem.)
+
+  Changes affecting documentation
+
+    The Theory file mentions naming issues earlier, as these seem to be
+    poorly publicized (thanks to Gilmore Davidson for reporting the problem).
+
+    tz-link.htm mentions Time Zone Database Parser (thanks to Howard Hinnant).
+
+    Mention that Herbert Samuel introduced the term "Summer Time".
+
+
+Release 2015e - 2015-06-13 10:56:02 -0700
+
+  Changes affecting future timestamps
+
+    Morocco will suspend DST from 2015-06-14 03:00 through 2015-07-19 02:00,
+    not 06-13 and 07-18 as we had guessed.  (Thanks to Milamber.)
+
+    Assume Cayman Islands will observe DST starting next year, using US rules.
+    Although it isn't guaranteed, it is the most likely.
+
+  Changes affecting data format
+
+    The file 'iso3166.tab' now uses UTF-8, so that its entries can better
+    spell the names of Åland Islands, Côte d'Ivoire, and Réunion.
+
+  Changes affecting code
+
+    When displaying data, tzselect converts it to the current locale's
+    encoding if the iconv command works.  (Problem reported by random832.)
+
+    tzselect no longer mishandles Dominica, fixing a bug introduced
+    in Release 2014f.  (Problem reported by Owen Leibman.)
+
+    zic -l no longer fails when compiled with -DTZDEFAULT=\"/etc/localtime\".
+    This fixes a bug introduced in Release 2014f.
+    (Problem reported by Leonardo Chiquitto.)
+
+
+Release 2015d - 2015-04-24 08:09:46 -0700
+
+  Changes affecting future timestamps
+
+    Egypt will not observe DST in 2015 and will consider canceling it
+    permanently.  For now, assume no DST indefinitely.
+    (Thanks to Ahmed Nazmy and Tim Parenti.)
+
+  Changes affecting past timestamps
+
+    America/Whitehorse switched from UT -09 to -08 on 1967-05-28, not
+    1966-07-01.  Also, Yukon's time zone history is documented better.
+    (Thanks to Brian Inglis and Dennis Ferguson.)
+
+  Change affecting past and future time zone abbreviations
+
+    The abbreviations for Hawaii-Aleutian standard and daylight times
+    have been changed from HAST/HADT to HST/HDT, as per US Government
+    Printing Office style.  This affects only America/Adak since 1983,
+    as America/Honolulu was already using the new style.
+
+  Changes affecting code
+
+   zic has some minor performance improvements.
+
+
+Release 2015c - 2015-04-11 08:55:55 -0700
+
+  Changes affecting future timestamps
+
+    Egypt's spring-forward transition is at 24:00 on April's last Thursday,
+    not 00:00 on April's last Friday.  2015's transition will therefore be on
+    Thursday, April 30 at 24:00, not Friday, April 24 at 00:00.  Similar fixes
+    apply to 2026, 2037, 2043, etc.  (Thanks to Steffen Thorsen.)
+
+  Changes affecting past timestamps
+
+    The following changes affect some pre-1991 Chile-related timestamps
+    in America/Santiago, Antarctica/Palmer, and Pacific/Easter.
+
+      The 1910 transition was January 10, not January 1.
+
+      The 1918 transition was September 10, not September 1.
+
+      The UT -04 time observed from 1932 to 1942 is now considered to
+      be standard time, not year-round DST.
+
+      Santiago observed DST (UT -03) from 1946-07-15 through
+      1946-08-31, then reverted to standard time, then switched to -05
+      on 1947-04-01.
+
+      Assume transitions before 1968 were at 00:00, since we have no data
+      saying otherwise.
+
+      The spring 1988 transition was 1988-10-09, not 1988-10-02.
+      The fall 1990 transition was 1990-03-11, not 1990-03-18.
+
+      Assume no UT offset change for Pacific/Easter on 1890-01-01,
+      and omit all transitions on Pacific/Easter from 1942 through 1946
+      since we have no data suggesting that they existed.
+
+    One more zone has been turned into a link, as it differed
+    from an existing zone only for older timestamps.  As usual,
+    this change affects UT offsets in pre-1970 timestamps only.
+    The zone's old contents have been moved to the 'backzone' file.
+    The affected zone is America/Montreal.
+
+  Changes affecting commentary
+
+    Mention the TZUpdater tool.
+
+    Mention "The Time Now".  (Thanks to Brandon Ramsey.)
+
+
+Release 2015b - 2015-03-19 23:28:11 -0700
+
+  Changes affecting future timestamps
+
+    Mongolia will start observing DST again this year, from the last
+    Saturday in March at 02:00 to the last Saturday in September at 00:00.
+    (Thanks to Ganbold Tsagaankhuu.)
+
+    Palestine will start DST on March 28, not March 27.  Also,
+    correct the fall 2014 transition from September 26 to October 24.
+    Adjust future predictions accordingly.  (Thanks to Steffen Thorsen.)
+
+  Changes affecting past timestamps
+
+    The 1982 zone shift in Pacific/Easter has been corrected, fixing a 2015a
+    regression.  (Thanks to Stuart Bishop for reporting the problem.)
+
+    Some more zones have been turned into links, when they differed
+    from existing zones only for older timestamps.  As usual,
+    these changes affect UT offsets in pre-1970 timestamps only.
+    Their old contents have been moved to the 'backzone' file.
+    The affected zones are: America/Antigua, America/Cayman,
+    Pacific/Midway, and Pacific/Saipan.
+
+  Changes affecting time zone abbreviations
+
+    Correct the 1992-2010 DST abbreviation in Volgograd from "MSK" to "MSD".
+    (Thanks to Hank W.)
+
+  Changes affecting code
+
+    Fix integer overflow bug in reference 'mktime' implementation.
+    (Problem reported by Jörg Richter.)
+
+    Allow -Dtime_tz=time_t compilations, and allow -Dtime_tz=... libraries
+    to be used in the same executable as standard-library time_t functions.
+    (Problems reported by Bradley White.)
+
+  Changes affecting commentary
+
+    Cite the recent Mexican decree changing Quintana Roo's time zone.
+    (Thanks to Carlos Raúl Perasso.)
+
+    Likewise for the recent Chilean decree.  (Thanks to Eduardo Romero Urra.)
+
+    Update info about Mars time.
+
+
+Release 2015a - 2015-01-29 22:35:20 -0800
+
+  Changes affecting future timestamps
+
+    The Mexican state of Quintana Roo, represented by America/Cancun,
+    will shift from Central Time with DST to Eastern Time without DST
+    on 2015-02-01 at 02:00.  (Thanks to Steffen Thorsen and Gwillim Law.)
+
+    Chile will not change clocks in April or thereafter; its new standard time
+    will be its old daylight saving time.  This affects America/Santiago,
+    Pacific/Easter, and Antarctica/Palmer.  (Thanks to Juan Correa.)
+
+    New leap second 2015-06-30 23:59:60 UTC as per IERS Bulletin C 49.
+    (Thanks to Tim Parenti.)
+
+  Changes affecting past timestamps
+
+    Iceland observed DST in 1919 and 1921, and its 1939 fallback
+    transition was Oct. 29, not Nov. 29.  Remove incorrect data from
+    Shanks about time in Iceland between 1837 and 1908.
+
+    Some more zones have been turned into links, when they differed
+    from existing zones only for older timestamps.  As usual,
+    these changes affect UT offsets in pre-1970 timestamps only.
+    Their old contents have been moved to the 'backzone' file.
+    The affected zones are: Asia/Aden, Asia/Bahrain, Asia/Kuwait,
+    and Asia/Muscat.
+
+  Changes affecting code
+
+    tzalloc now scrubs time zone abbreviations compatibly with the way
+    that tzset always has, by replacing invalid bytes with '_' and by
+    shortening too-long abbreviations.
+
+    tzselect ports to POSIX awk implementations, no longer mishandles
+    POSIX TZ settings when GNU awk is used, and reports POSIX TZ
+    settings to the user.  (Thanks to Stefan Kuhn.)
+
+  Changes affecting build procedure
+
+    'make check' now checks for links to links in the data.
+    One such link (for Africa/Asmera) has been fixed.
+    (Thanks to Stephen Colebourne for pointing out the problem.)
+
+  Changes affecting commentary
+
+    The leapseconds file commentary now mentions the expiration date.
+    (Problem reported by Martin Burnicki.)
+
+    Update Mexican Library of Congress URL.
+
+
+Release 2014j - 2014-11-10 17:37:11 -0800
+
+  Changes affecting current and future timestamps
+
+    Turks & Caicos' switch from US eastern time to UT -04 year-round
+    did not occur on 2014-11-02 at 02:00.  It's currently scheduled
+    for 2015-11-01 at 02:00.  (Thanks to Chris Walton.)
+
+  Changes affecting past timestamps
+
+    Many pre-1989 timestamps have been corrected for Asia/Seoul and
+    Asia/Pyongyang, based on sources for the Korean-language Wikipedia
+    entry for time in Korea.  (Thanks to Sanghyuk Jung.)  Also, no
+    longer guess that Pyongyang mimicked Seoul time after World War II,
+    as this is politically implausible.
+
+    Some more zones have been turned into links, when they differed
+    from existing zones only for older timestamps.  As usual,
+    these changes affect UT offsets in pre-1970 timestamps only.
+    Their old contents have been moved to the 'backzone' file.
+    The affected zones are: Africa/Addis_Ababa, Africa/Asmara,
+    Africa/Dar_es_Salaam, Africa/Djibouti, Africa/Kampala,
+    Africa/Mogadishu, Indian/Antananarivo, Indian/Comoro, and
+    Indian/Mayotte.
+
+  Changes affecting commentary
+
+    The commentary is less enthusiastic about Shanks as a source,
+    and is more careful to distinguish UT from UTC.
+
+
+Release 2014i - 2014-10-21 22:04:57 -0700
+
+  Changes affecting future timestamps
+
+    Pacific/Fiji will observe DST from 2014-11-02 02:00 to 2015-01-18 03:00.
+    (Thanks to Ken Rylander for the heads-up.)  Guess that future
+    years will use a similar pattern.
+
+    A new Zone Pacific/Bougainville, for the part of Papua New Guinea
+    that plans to switch from UT +10 to +11 on 2014-12-28 at 02:00.
+    (Thanks to Kiley Walbom for the heads-up.)
+
+  Changes affecting time zone abbreviations
+
+    Since Belarus is not changing its clocks even though Moscow is,
+    the time zone abbreviation in Europe/Minsk is changing from FET
+    to its more-traditional value MSK on 2014-10-26 at 01:00.
+    (Thanks to Alexander Bokovoy for the heads-up about Belarus.)
+
+    The new abbreviation IDT stands for the pre-1976 use of UT +08 in
+    Indochina, to distinguish it better from ICT (+07).
+
+  Changes affecting past timestamps
+
+    Many timestamps have been corrected for Asia/Ho_Chi_Minh before 1976
+    (thanks to Trần Ngọc Quân for an indirect pointer to Trần Tiến Bình's
+    authoritative book).  Asia/Ho_Chi_Minh has been added to
+    zone1970.tab, to give tzselect users in Vietnam two choices,
+    since north and south Vietnam disagreed after our 1970 cutoff.
+
+    Asia/Phnom_Penh and Asia/Vientiane have been turned into links, as
+    they differed from existing zones only for older timestamps.  As
+    usual, these changes affect pre-1970 timestamps only.  Their old
+    contents have been moved to the 'backzone' file.
+
+  Changes affecting code
+
+    The time-related library functions now set errno on failure, and
+    some crashes in the new tzalloc-related library functions have
+    been fixed.  (Thanks to Christos Zoulas for reporting most of
+    these problems and for suggesting fixes.)
+
+    If USG_COMPAT is defined and the requested timestamp is standard time,
+    the tz library's localtime and mktime functions now set the extern
+    variable timezone to a value appropriate for that timestamp; and
+    similarly for ALTZONE, daylight saving time, and the altzone variable.
+    This change is a companion to the tzname change in 2014h, and is
+    designed to make timezone and altzone more compatible with tzname.
+
+    The tz library's functions now set errno to EOVERFLOW if they fail
+    because the result cannot be represented.  ctime and ctime_r now
+    return NULL and set errno when a timestamp is out of range, rather
+    than having undefined behavior.
+
+    Some bugs associated with the new 2014g functions have been fixed.
+    This includes a bug that largely incapacitated the new functions
+    time2posix_z and posix2time_z.  (Thanks to Christos Zoulas.)
+    It also includes some uses of uninitialized variables after tzalloc.
+    The new code uses the standard type 'ssize_t', which the Makefile
+    now gives porting advice about.
+
+  Changes affecting commentary
+
+    Updated URLs for NRC Canada (thanks to Matt Johnson and Brian Inglis).
+
+
+Release 2014h - 2014-09-25 18:59:03 -0700
+
+  Changes affecting past timestamps
+
+    America/Jamaica's 1974 spring-forward transition was Jan. 6, not Apr. 28.
+
+    Shanks says Asia/Novokuznetsk switched from LMT (not "NMT") on 1924-05-01,
+    not 1920-01-06.  The old entry was based on a misinterpretation of Shanks.
+
+    Some more zones have been turned into links, when they differed
+    from existing zones only for older timestamps.  As usual,
+    these changes affect UT offsets in pre-1970 timestamps only.
+    Their old contents have been moved to the 'backzone' file.
+    The affected zones are: Africa/Blantyre, Africa/Bujumbura,
+    Africa/Gaborone, Africa/Harare, Africa/Kigali, Africa/Lubumbashi,
+    Africa/Lusaka, Africa/Maseru, and Africa/Mbabane.
+
+  Changes affecting code
+
+    zdump -V and -v now output gmtoff= values on all platforms,
+    not merely on platforms defining TM_GMTOFF.
+
+    The tz library's localtime and mktime functions now set tzname to a value
+    appropriate for the requested timestamp, and zdump now uses this
+    on platforms not defining TM_ZONE, fixing a 2014g regression.
+    (Thanks to Tim Parenti for reporting the problem.)
+
+    The tz library no longer sets tzname if localtime or mktime fails.
+
+    zdump -c no longer mishandles transitions near year boundaries.
+    (Thanks to Tim Parenti for reporting the problem.)
+
+    An access to uninitialized data has been fixed.
+    (Thanks to Jörg Richter for reporting the problem.)
+
+    When THREAD_SAFE is defined, the code ports to the C11 memory model.
+    A memory leak has been fixed if ALL_STATE and THREAD_SAFE are defined
+    and two threads race to initialize data used by gmtime-like functions.
+    (Thanks to Andy Heninger for reporting the problems.)
+
+  Changes affecting build procedure
+
+    'make check' now checks better for properly-sorted data.
+
+  Changes affecting documentation and commentary
+
+    zdump's gmtoff=N output is now documented, and its isdst=D output
+    is now documented to possibly output D values other than 0 or 1.
+
+    zdump -c's treatment of years is now documented to use the
+    Gregorian calendar and Universal Time without leap seconds,
+    and its behavior at cutoff boundaries is now documented better.
+    (Thanks to Arthur David Olson and Tim Parenti for reporting the problems.)
+
+    Programs are now documented to use the proleptic Gregorian calendar.
+    (Thanks to Alan Barrett for the suggestion.)
+
+    Fractional-second GMT offsets have been documented for civil time
+    in 19th-century Chennai, Jakarta, and New York.
+
+
+Release 2014g - 2014-08-28 12:31:23 -0700
+
+  Changes affecting future timestamps
+
+    Turks & Caicos is switching from US eastern time to UT -04
+    year-round, modeled as a switch on 2014-11-02 at 02:00.
+    [As noted in 2014j, this switch was later delayed.]
+
+  Changes affecting past timestamps
+
+    Time in Russia or the USSR before 1926 or so has been corrected by
+    a few seconds in the following zones: Asia/Irkutsk,
+    Asia/Krasnoyarsk, Asia/Omsk, Asia/Samarkand, Asia/Tbilisi,
+    Asia/Vladivostok, Asia/Yakutsk, Europe/Riga, Europe/Samara.  For
+    Asia/Yekaterinburg the correction is a few minutes.  (Thanks to
+    Vladimir Karpinsky.)
+
+    The Portuguese decree of 1911-05-26 took effect on 1912-01-01.
+    This affects 1911 timestamps in Africa/Bissau, Africa/Luanda,
+    Atlantic/Azores, and Atlantic/Madeira.  Also, Lisbon's pre-1912
+    GMT offset was -0:36:45 (rounded from -0:36:44.68), not -0:36:32.
+    (Thanks to Stephen Colebourne for pointing to the decree.)
+
+    Asia/Dhaka ended DST on 2009-12-31 at 24:00, not 23:59.
+
+    A new file 'backzone' contains data which may appeal to
+    connoisseurs of old timestamps, although it is out of scope for
+    the tz database, is often poorly sourced, and contains some data
+    that is known to be incorrect.  The new file is not recommended
+    for ordinary use and its entries are not installed by default.
+    (Thanks to Lester Caine for the high-quality Jersey, Guernsey, and
+    Isle of Man entries.)
+
+    Some more zones have been turned into links, when they differed
+    from existing zones only for older timestamps.  As usual,
+    these changes affect UT offsets in pre-1970 timestamps only.
+    Their old contents have been moved to the 'backzone' file.
+    The affected zones are: Africa/Bangui, Africa/Brazzaville,
+    Africa/Douala, Africa/Kinshasa, Africa/Libreville, Africa/Luanda,
+    Africa/Malabo, Africa/Niamey, and Africa/Porto-Novo.
+
+  Changes affecting code
+
+    Unless NETBSD_INSPIRED is defined to 0, the tz library now
+    supplies functions for creating and using objects that represent
+    timezones. The new functions are tzalloc, tzfree, localtime_rz,
+    mktime_z, and (if STD_INSPIRED is also defined) posix2time_z and
+    time2posix_z.  They are intended for performance: for example,
+    localtime_rz (unlike localtime_r) is trivially thread-safe without
+    locking.  (Thanks to Christos Zoulas for proposing NetBSD-inspired
+    functions, and to Alan Barrett and Jonathan Lennox for helping to
+    debug the change.)
+
+    zdump now builds with the tz library unless USE_LTZ is defined to 0,
+    This lets zdump use tz features even if the system library lacks them.
+    To build zdump with the system library, use 'make CFLAGS=-DUSE_LTZ=0
+    TZDOBJS=zdump.o CHECK_TIME_T_ALTERNATIVES='.
+
+    zdump now uses localtime_rz if available, as it's significantly faster,
+    and it can help zdump better diagnose invalid timezone names.
+    Define HAVE_LOCALTIME_RZ to 0 to suppress this.  HAVE_LOCALTIME_RZ
+    defaults to 1 if NETBSD_INSPIRED && USE_LTZ.  When localtime_rz is
+    not available, zdump now uses localtime_r and tzset if available,
+    as this is a bit cleaner and faster than plain localtime.  Compile
+    with -DHAVE_LOCALTIME_R=0 and/or -DHAVE_TZSET=0 if your system
+    lacks these two functions.
+
+    If THREAD_SAFE is defined to 1, the tz library is now thread-safe.
+    Although not needed for tz's own applications, which are single-threaded,
+    this supports POSIX better if the tz library is used in multithreaded apps.
+
+    Some crashes have been fixed when zdump or the tz library is given
+    invalid or outlandish input.
+
+    The tz library no longer mishandles leap seconds on platforms with
+    unsigned time_t in timezones that lack ordinary transitions after 1970.
+
+    The tz code now attempts to infer TM_GMTOFF and TM_ZONE if not
+    already defined, to make it easier to configure on common platforms.
+    Define NO_TM_GMTOFF and NO_TM_ZONE to suppress this.
+
+    Unless the new macro UNINIT_TRAP is defined to 1, the tz code now
+    assumes that reading uninitialized memory yields garbage values
+    but does not cause other problems such as traps.
+
+    If TM_GMTOFF is defined and UNINIT_TRAP is 0, mktime is now
+    more likely to guess right for ambiguous timestamps near
+    transitions where tm_isdst does not change.
+
+    If HAVE_STRFTIME_L is defined to 1, the tz library now defines
+    strftime_l for compatibility with recent versions of POSIX.
+    Only the C locale is supported, though.  HAVE_STRFTIME_L defaults
+    to 1 on recent POSIX versions, and to 0 otherwise.
+
+    tzselect -c now uses a hybrid distance measure that works better
+    in Africa.  (Thanks to Alan Barrett for noting the problem.)
+
+    The C source code now ports to NetBSD when GCC_DEBUG_FLAGS is used,
+    or when time_tz is defined.
+
+    When HAVE_UTMPX_H is set the 'date' command now builds on systems
+    whose <utmpx.h> file does not define WTMPX_FILE, and when setting
+    the date it updates the wtmpx file if _PATH_WTMPX is defined.
+    This affects GNU/Linux and similar systems.
+
+    For easier maintenance later, some C code has been simplified,
+    some lint has been removed, and the code has been tweaked so that
+    plain 'make' is more likely to work.
+
+    The C type 'bool' is now used for boolean values, instead of 'int'.
+
+    The long-obsolete LOCALE_HOME code has been removed.
+
+    The long-obsolete 'gtime' function has been removed.
+
+  Changes affecting build procedure
+
+    'zdump' no longer links in ialloc.o, as it's not needed.
+
+    'make check_time_t_alternatives' no longer assumes GNU diff.
+
+  Changes affecting distribution tarballs
+
+    The files checktab.awk and zoneinfo2tdf.pl are now distributed in
+    the tzdata tarball instead of the tzcode tarball, since they help
+    maintain the data.  The NEWS and Theory files are now also
+    distributed in the tzdata tarball, as they're relevant for data.
+    (Thanks to Alan Barrett for pointing this out.)  Also, the
+    leapseconds.awk file is no longer distributed in the tzcode
+    tarball, since it belongs in the tzdata tarball (where 2014f
+    inadvertently also distributed it).
+
+  Changes affecting documentation and commentary
+
+    A new file CONTRIBUTING is distributed.  (Thanks to Tim Parenti for
+    suggesting a CONTRIBUTING file, and to Tony Finch and Walter Harms
+    for debugging it.)
+
+    The man pages have been updated to use function prototypes,
+    to document thread-safe variants like localtime_r, and to document
+    the NetBSD-inspired functions tzalloc, tzfree, localtime_rz, and
+    mktime_z.
+
+    The fields in Link lines have been renamed to be more descriptive
+    and more like the parameters of 'ln'.  LINK-FROM has become TARGET,
+    and LINK-TO has become LINK-NAME.
+
+    tz-link.htm mentions the IETF's tzdist working group; Windows
+    Runtime etc. (thanks to Matt Johnson); and HP-UX's tztab.
+
+    Some broken URLs have been fixed in the commentary.  (Thanks to
+    Lester Caine.)
+
+    Commentary about Philippines DST has been updated, and commentary
+    on pre-1970 time in India has been added.
+
+
+Release 2014f - 2014-08-05 17:42:36 -0700
+
+  Changes affecting future timestamps
+
+    Russia will subtract an hour from most of its time zones on 2014-10-26
+    at 02:00 local time.  (Thanks to Alexander Krivenyshev.)
+    There are a few exceptions: Magadan Oblast (Asia/Magadan) and Zabaykalsky
+    Krai are subtracting two hours; conversely, Chukotka Autonomous Okrug
+    (Asia/Anadyr), Kamchatka Krai (Asia/Kamchatka), Kemerovo Oblast
+    (Asia/Novokuznetsk), and the Samara Oblast and the Udmurt Republic
+    (Europe/Samara) are not changing their clocks.  The changed zones are
+    Europe/Kaliningrad, Europe/Moscow, Europe/Simferopol, Europe/Volgograd,
+    Asia/Yekaterinburg, Asia/Omsk, Asia/Novosibirsk, Asia/Krasnoyarsk,
+    Asia/Irkutsk, Asia/Yakutsk, Asia/Vladivostok, Asia/Khandyga,
+    Asia/Sakhalin, and Asia/Ust-Nera; Asia/Magadan will have two hours
+    subtracted; and Asia/Novokuznetsk's time zone abbreviation is affected,
+    but not its UTC offset.  Two zones are added: Asia/Chita (split
+    from Asia/Yakutsk, and also with two hours subtracted) and
+    Asia/Srednekolymsk (split from Asia/Magadan, but with only one hour
+    subtracted).  (Thanks to Tim Parenti for much of the above.)
+
+  Changes affecting time zone abbreviations
+
+    Australian eastern time zone abbreviations are now AEST/AEDT not EST,
+    and similarly for the other Australian zones.  That is, for eastern
+    standard and daylight saving time the abbreviations are AEST and AEDT
+    instead of the former EST for both; similarly, ACST/ACDT, ACWST/ACWDT,
+    and AWST/AWDT are now used instead of the former CST, CWST, and WST.
+    This change does not affect UT offsets, only time zone abbreviations.
+    (Thanks to Rich Tibbett and many others.)
+
+    Asia/Novokuznetsk shifts from NOVT to KRAT (remaining on UT +07)
+    effective 2014-10-26 at 02:00 local time.
+
+    The time zone abbreviation for Xinjiang Time (observed in Ürümqi)
+    has been changed from URUT to XJT.  (Thanks to Luther Ma.)
+
+    Prefer MSK/MSD for Moscow time in Russia, even in other cities.
+    Similarly, prefer EET/EEST for eastern European time in Russia.
+
+    Change time zone abbreviations in (western) Samoa to use "ST" and
+    "DT" suffixes, as this is more likely to match common practice.
+    Prefix "W" to (western) Samoa time when its standard-time offset
+    disagrees with that of American Samoa.
+
+    America/Metlakatla now uses PST, not MeST, to abbreviate its time zone.
+
+    Time zone abbreviations have been updated for Japan's two time
+    zones used 1896-1937.  JWST now stands for Western Standard
+    Time, and JCST for Central Standard Time (formerly this was CJT).
+    These abbreviations are now used for time in Korea, Taiwan,
+    and Sakhalin while controlled by Japan.
+
+  Changes affecting past timestamps
+
+    China's five zones have been simplified to two, since the post-1970
+    differences in the other three seem to have been imaginary.  The
+    zones Asia/Harbin, Asia/Chongqing, and Asia/Kashgar have been
+    removed; backwards-compatibility links still work, albeit with
+    different behaviors for timestamps before May 1980.  Asia/Urumqi's
+    1980 transition to UT +08 has been removed, so that it is now at
+    +06 and not +08.  (Thanks to Luther Ma and to Alois Treindl;
+    Treindl sent helpful translations of two papers by Guo Qingsheng.)
+
+    Some zones have been turned into links, when they differed from existing
+    zones only for older UT offsets where data entries were likely invented.
+    These changes affect UT offsets in pre-1970 timestamps only.  This is
+    similar to the change in release 2013e, except this time for western
+    Africa.  The affected zones are: Africa/Bamako, Africa/Banjul,
+    Africa/Conakry, Africa/Dakar, Africa/Freetown, Africa/Lome,
+    Africa/Nouakchott, Africa/Ouagadougou, Africa/Sao_Tome, and
+    Atlantic/St_Helena.  This also affects the backwards-compatibility
+    link Africa/Timbuktu.  (Thanks to Alan Barrett, Stephen Colebourne,
+    Tim Parenti, and David Patte for reporting problems in earlier
+    versions of this change.)
+
+    Asia/Shanghai's pre-standard-time UT offset has been changed from
+    8:05:57 to 8:05:43, the location of Xujiahui Observatory.  Its
+    transition to standard time has been changed from 1928 to 1901.
+
+    Asia/Taipei switched to JWST on 1896-01-01, then to JST on 1937-10-01,
+    then to CST on 1945-09-21 at 01:00, and did not observe DST in 1945.
+    In 1946 it observed DST from 05-15 through 09-30; in 1947
+    from 04-15 through 10-31; and in 1979 from 07-01 through 09-30.
+    (Thanks to Yu-Cheng Chuang.)
+
+    Asia/Riyadh's transition to standard time is now 1947-03-14, not 1950.
+
+    Europe/Helsinki's 1942 fall-back transition was 10-04 at 01:00, not
+    10-03 at 00:00.  (Thanks to Konstantin Hyppönen.)
+
+    Pacific/Pago_Pago has been changed from UT -11:30 to -11 for the
+    period from 1911 to 1950.
+
+    Pacific/Chatham has been changed to New Zealand standard time plus
+    45 minutes for the period before 1957, reflecting a 1956 remark in
+    the New Zealand parliament.
+
+    Europe/Budapest has several pre-1946 corrections: in 1918 the transition
+    out of DST was on 09-16, not 09-29; in 1919 it was on 11-24, not 09-15; in
+    1945 it was on 11-01, not 11-03; in 1941 the transition to DST was 04-08
+    not 04-06 at 02:00; and there was no DST in 1920.
+
+    Africa/Accra is now assumed to have observed DST from 1920 through 1935.
+
+    Time in Russia before 1927 or so has been corrected by a few seconds in
+    the following zones: Europe/Moscow, Asia/Irkutsk, Asia/Tbilisi,
+    Asia/Tashkent, Asia/Vladivostok, Asia/Yekaterinburg, Europe/Helsinki, and
+    Europe/Riga.  Also, Moscow's location has been changed to its Kilometer 0
+    point.  (Thanks to Vladimir Karpinsky for the Moscow changes.)
+
+  Changes affecting data format
+
+    A new file 'zone1970.tab' supersedes 'zone.tab' in the installed data.
+    The new file's extended format allows multiple country codes per zone.
+    The older file is still installed but is deprecated; its format is
+    not changing and it will still be distributed for a while, but new
+    applications should use the new file.
+
+    The new file format simplifies maintenance of obscure locations.
+    To test this, it adds coverage for the Crozet Islands and the
+    Scattered Islands.  (Thanks to Tobias Conradi and Antoine Leca.)
+
+    The file 'iso3166.tab' is planned to switch from ASCII to UTF-8.
+    It is still ASCII now, but commentary about the switch has been added.
+    The new file 'zone1970.tab' already uses UTF-8.
+
+  Changes affecting code
+
+    'localtime', 'mktime', etc. now use much less stack space if ALL_STATE
+    is defined.  (Thanks to Elliott Hughes for reporting the problem.)
+
+    'zic' no longer mishandles input when ignoring case in locales that
+    are not compatible with English, e.g., unibyte Turkish locales when
+    compiled with HAVE_GETTEXT.
+
+    Error diagnostics of 'zic' and 'yearistype' have been reworded so that
+    they no longer use ASCII '-' as if it were a dash.
+
+    'zic' now rejects output file names that contain '.' or '..' components.
+    (Thanks to Tim Parenti for reporting the problem.)
+
+    'zic -v' now warns about output file names that do not follow
+    POSIX rules, or that contain a digit or '.'.  (Thanks to Arthur
+    David Olson for starting the ball rolling on this.)
+
+    Some lint has been removed when using GCC_DEBUG_FLAGS with GCC 4.9.0.
+
+  Changes affecting build procedure
+
+    'zic' no longer links in localtime.o and asctime.o, as they're not needed.
+    (Thanks to John Cochran.)
+
+  Changes affecting documentation and commentary
+
+    The 'Theory' file documents legacy names, the longstanding
+    exceptions to the POSIX-inspired file name rules.
+
+    The 'zic' documentation clarifies the role of time types when
+    interpreting dates.  (Thanks to Arthur David Olson.)
+
+    Documentation and commentary now prefer UTF-8 to US-ASCII,
+    allowing the use of proper accents in foreign words and names.
+    Code and data have not changed because of this.  (Thanks to
+    Garrett Wollman, Ian Abbott, and Guy Harris for helping to debug
+    this.)
+
+    Non-HTML documentation and commentary now use plain-text URLs instead of
+    HTML insertions, and are more consistent about bracketing URLs when they
+    are not already surrounded by white space.  (Thanks to suggestions by
+    Steffen Nurpmeso.)
+
+    There is new commentary about Xujiahui Observatory, the five time-zone
+    project in China from 1918 to 1949, timekeeping in Japanese-occupied
+    Shanghai, and Tibet Time in the 1950s.  The sharp-eyed can spot the
+    warlord Jin Shuren in the data.
+
+    Commentary about the coverage of each Russian zone has been standardized.
+    (Thanks to Tim Parenti.)
+
+    There is new commentary about contemporary timekeeping in Ethiopia.
+
+    Obsolete comments about a 2007 proposal for DST in Kuwait has been removed.
+
+    There is new commentary about time in Poland in 1919.
+
+    Proper credit has been given to DST inventor George Vernon Hudson.
+
+    Commentary about time in Metlakatla, AK and Resolute, NU has been
+    improved, with a new source for the former.
+
+    In zone.tab, Pacific/Easter no longer mentions Salas y Gómez, as it
+    is uninhabited.
+
+    Commentary about permanent Antarctic bases has been updated.
+
+    Several typos have been corrected.  (Thanks to Tim Parenti for
+    contributing some of these fixes.)
+
+    tz-link.htm now mentions the JavaScript libraries Moment Timezone,
+    TimezoneJS.Date, Walltime-js, and Timezone.  (Thanks to a heads-up
+    from Matt Johnson.)  Also, it mentions the Go 'latlong' package.
+    (Thanks to a heads-up from Dirkjan Ochtman.)
+
+    The files usno1988, usno1989, usno1989a, usno1995, usno1997, and usno1998
+    have been removed.  These obsolescent US Naval Observatory entries were no
+    longer helpful for maintenance.  (Thanks to Tim Parenti for the suggestion.)
+
+
+Release 2014e - 2014-06-12 21:53:52 -0700
+
+  Changes affecting near-future timestamps
+
+    Egypt's 2014 Ramadan-based transitions are June 26 and July 31 at 24:00.
+    (Thanks to Imed Chihi.)  Guess that from 2015 on Egypt will temporarily
+    switch to standard time at 24:00 the last Thursday before Ramadan, and
+    back to DST at 00:00 the first Friday after Ramadan.
+
+    Similarly, Morocco's are June 28 at 03:00 and August 2 at 02:00.  (Thanks
+    to Milamber Space Network.)  Guess that from 2015 on Morocco will
+    temporarily switch to standard time at 03:00 the last Saturday before
+    Ramadan, and back to DST at 02:00 the first Saturday after Ramadan.
+
+  Changes affecting past timestamps
+
+    The abbreviation "MSM" (Moscow Midsummer Time) is now used instead of
+    "MSD" for Moscow's double daylight time in summer 1921.  Also, a typo
+    "VLASST" has been repaired to be "VLAST" for Vladivostok summer time
+    in 1991.  (Thanks to Hank W. for reporting the problems.)
+
+  Changes affecting commentary
+
+    tz-link.htm now cites RFC 7265 for jCal, mentions PTP and the
+    draft CalDAV extension, updates URLs for TSP, TZInfo, IATA, and
+    removes stale pointers to World Time Explorer and WORLDTIME.
+
+
+Release 2014d - 2014-05-27 21:34:40 -0700
+
+  Changes affecting code
+
+    zic no longer generates files containing timestamps before the Big Bang.
+    This works around GNOME glib bug 878
+    <https://gitlab.gnome.org/GNOME/glib/issues/878>
+    (Thanks to Leonardo Chiquitto for reporting the bug, and to
+    Arthur David Olson and James Cloos for suggesting improvements to the fix.)
+
+  Changes affecting documentation
+
+    tz-link.htm now mentions GNOME.
+
+
+Release 2014c - 2014-05-13 07:44:13 -0700
+
+  Changes affecting near-future timestamps
+
+    Egypt observes DST starting 2014-05-15 at 24:00.
+    (Thanks to Ahmad El-Dardiry and Gunther Vermier.)
+    Details have not been announced, except that DST will not be observed
+    during Ramadan.  Guess that DST will stop during the same Ramadan dates as
+    Morocco, and that Egypt's future spring and fall transitions will be the
+    same as 2010 when it last observed DST, namely April's last Friday at
+    00:00 to September's last Thursday at 23:00 standard time.  Also, guess
+    that Ramadan transitions will be at 00:00 standard time.
+
+  Changes affecting code
+
+    zic now generates transitions for minimum time values, eliminating guesswork
+    when handling low-valued timestamps.  (Thanks to Arthur David Olson.)
+
+    Port to Cygwin sans glibc.  (Thanks to Arthur David Olson.)
+
+  Changes affecting commentary and documentation
+
+    Remove now-confusing comment about Jordan.  (Thanks to Oleksii Nochovnyi.)
+
+
+Release 2014b - 2014-03-24 21:28:50 -0700
+
+  Changes affecting near-future timestamps
+
+    Crimea switches to Moscow time on 2014-03-30 at 02:00 local time.
+    (Thanks to Alexander Krivenyshev.)  Move its zone.tab entry from UA to RU.
+
+    New entry for Troll station, Antarctica.  (Thanks to Paul-Inge Flakstad and
+    Bengt-Inge Larsson.)  This is currently an approximation; a better version
+    will require the zic and localtime fixes mentioned below, and the plan is
+    to wait for a while until at least the zic fixes propagate.
+
+  Changes affecting code
+
+    'zic' and 'localtime' no longer reject locations needing four transitions
+    per year for the foreseeable future.  (Thanks to Andrew Main (Zefram).)
+    Also, 'zic' avoids some unlikely failures due to integer overflow.
+
+  Changes affecting build procedure
+
+    'make check' now detects Rule lines defined but never used.
+    The NZAQ rules, an instance of this problem, have been removed.
+
+  Changes affecting commentary and documentation
+
+    Fix Tuesday/Thursday typo in description of time in Israel.
+    (Thanks to Bert Katz via Pavel Kharitonov and Mike Frysinger.)
+
+    Microsoft Windows 8.1 doesn't support tz database names.  (Thanks
+    to Donald MacQueen.)  Instead, the Microsoft Windows Store app
+    library supports them.
+
+    Add comments about Johnston Island time in the 1960s.
+    (Thanks to Lyle McElhaney.)
+
+    Morocco's 2014 DST start will be as predicted.
+    (Thanks to Sebastien Willemijns.)
+
+
+Release 2014a - 2014-03-07 23:30:29 -0800
+
+  Changes affecting near-future timestamps
+
+    Turkey begins DST on 2014-03-31, not 03-30.  (Thanks to Faruk Pasin for
+    the heads-up, and to Tim Parenti for simplifying the update.)
+
+  Changes affecting past timestamps
+
+    Fiji ended DST on 2014-01-19 at 02:00, not the previously-scheduled 03:00.
+    (Thanks to Steffen Thorsen.)
+
+    Ukraine switched from Moscow to Eastern European time on 1990-07-01
+    (not 1992-01-01), and observed DST during the entire next winter.
+    (Thanks to Vladimir in Moscow via Alois Treindl.)
+
+    In 1988 Israel observed DST from 04-10 to 09-04, not 04-09 to 09-03.
+    (Thanks to Avigdor Finkelstein.)
+
+  Changes affecting code
+
+    A uninitialized-storage bug in 'localtime' has been fixed.
+    (Thanks to Logan Chien.)
+
+  Changes affecting the build procedure
+
+    The settings for 'make check_web' now default to Ubuntu 13.10.
+
+  Changes affecting commentary and documentation
+
+    The boundary of the US Pacific time zone is given more accurately.
+    (Thanks to Alan Mintz.)
+
+    Chile's 2014 DST will be as predicted.  (Thanks to José Miguel Garrido.)
+
+    Paraguay's 2014 DST will be as predicted.  (Thanks to Carlos Raúl Perasso.)
+
+    Better descriptions of countries with same time zone history as
+    Trinidad and Tobago since 1970.  (Thanks to Alan Barrett for suggestion.)
+
+    Several changes affect tz-link.htm, the main web page.
+
+      Mention Time.is (thanks to Even Scharning) and WX-now (thanks to
+      David Braverman).
+
+      Mention xCal (Internet RFC 6321) and jCal.
+
+      Microsoft has some support for tz database names.
+
+      CLDR data formats include both XML and JSON.
+
+      Mention Maggiolo's map of solar vs standard time.
+      (Thanks to Arthur David Olson.)
+
+      Mention TZ4Net.  (Thanks to Matt Johnson.)
+
+      Mention the timezone-olson Haskell package.
+
+      Mention zeitverschiebung.net.  (Thanks to Martin Jäger.)
+
+      Remove moribund links to daylight-savings-time.info and to
+      Simple Timer + Clocks.
+
+      Update two links.  (Thanks to Oscar van Vlijmen.)
+
+      Fix some formatting glitches, e.g., remove random newlines from
+      abbr elements' title attributes.
+
+
+Release 2013i - 2013-12-17 07:25:23 -0800
+
+  Changes affecting near-future timestamps:
+
+    Jordan switches back to standard time at 00:00 on December 20, 2013.
+    The 2006-2011 transition schedule is planned to resume in 2014.
+    (Thanks to Steffen Thorsen.)
+
+  Changes affecting past timestamps:
+
+    In 2004, Cuba began DST on March 28, not April 4.
+    (Thanks to Steffen Thorsen.)
+
+  Changes affecting code
+
+    The compile-time flag NOSOLAR has been removed, as nowadays the
+    benefit of slightly shrinking runtime table size is outweighed by the
+    cost of disallowing potential future updates that exceed old limits.
+
+  Changes affecting documentation and commentary
+
+    The files solar87, solar88, and solar89 are no longer distributed.
+    They were a negative experiment - that is, a demonstration that
+    tz data can represent solar time only with some difficulty and error.
+    Their presence in the distribution caused confusion, as Riyadh
+    civil time was generally not solar time in those years.
+
+    tz-link.htm now mentions Noda Time.  (Thanks to Matt Johnson.)
+
+
+Release 2013h - 2013-10-25 15:32:32 -0700
+
+  Changes affecting current and future timestamps:
+
+    Libya has switched its UT offset back to +02 without DST, instead
+    of +01 with DST.  (Thanks to Even Scharning.)
+
+    Western Sahara (Africa/El_Aaiun) uses Morocco's DST rules.
+    (Thanks to Gwillim Law.)
+
+  Changes affecting future timestamps:
+
+    Acre and (we guess) western Amazonas will switch from UT -04 to -05
+    on 2013-11-10.  This affects America/Rio_Branco and America/Eirunepe.
+    (Thanks to Steffen Thorsen.)
+
+    Add entries for DST transitions in Morocco in the year 2038.
+    This avoids some year-2038 glitches introduced in 2013g.
+    (Thanks to Yoshito Umaoka for reporting the problem.)
+
+  Changes affecting API
+
+    The 'tzselect' command no longer requires the 'select' command,
+    and should now work with /bin/sh on more platforms.  It also works
+    around a bug in BusyBox awk before version 1.21.0.  (Thanks to
+    Patrick 'P. J.' McDermott and Alan Barrett.)
+
+  Changes affecting code
+
+    Fix localtime overflow bugs with 32-bit unsigned time_t.
+
+    zdump no longer assumes sscanf returns maximal values on overflow.
+
+  Changes affecting the build procedure
+
+    The builder can specify which programs to use, if any, instead of
+    'ar' and 'ranlib', and libtz.a is now built locally before being
+    installed.  (Thanks to Michael Forney.)
+
+    A dependency typo in the 'zdump' rule has been fixed.
+    (Thanks to Andrew Paprocki.)
+
+    The Makefile has been simplified by assuming that 'mkdir -p' and 'cp -f'
+    work as specified by POSIX.2-1992 or later; this is portable nowadays.
+
+    'make clean' no longer removes 'leapseconds', since it's
+    host-independent and is part of the distribution.
+
+    The unused makefile macros TZCSRCS, TZDSRCS, DATESRCS have been removed.
+
+  Changes affecting documentation and commentary
+
+    tz-link.htm now mentions TC TIMEZONE's draft time zone service protocol
+    (thanks to Mike Douglass) and TimezoneJS.Date (thanks to Jim Fehrle).
+
+    Update URLs in tz-link page.  Add URLs for Microsoft Windows, since
+    8.1 introduces tz support.  Remove URLs for Tru64 and UnixWare (no
+    longer maintained) and for old advisories.  SOFA now does C.
+
+Release 2013g - 2013-09-30 21:08:26 -0700
+
+  Changes affecting current and near-future timestamps
+
+    Morocco now observes DST from the last Sunday in March to the last
+    Sunday in October, not April to September respectively.  (Thanks
+    to Steffen Thorsen.)
+
+  Changes affecting 'zic'
+
+    'zic' now runs on platforms that lack both hard links and symlinks.
+    (Thanks to Theo Veenker for reporting the problem, for MinGW.)
+    Also, fix some bugs on platforms that lack hard links but have symlinks.
+
+    'zic -v' again warns that Asia/Tehran has no POSIX environment variable
+    to predict the far future, fixing a bug introduced in 2013e.
+
+  Changes affecting the build procedure
+
+    The 'leapseconds' file is again put into the tzdata tarball.
+    Also, 'leapseconds.awk', so tzdata is self-contained.  (Thanks to
+    Matt Burgess and Ian Abbott.)  The timestamps of these and other
+    dependent files in tarballs are adjusted more consistently.
+
+  Changes affecting documentation and commentary
+
+    The README file is now part of the data tarball as well as the code.
+    It now states that files are public domain unless otherwise specified.
+    (Thanks to Andrew Main (Zefram) for asking for clarifications.)
+    Its details about the 1989 release moved to a place of honor near
+    the end of NEWS.
+
+
+Release 2013f - 2013-09-24 23:37:36 -0700
+
+  Changes affecting near-future timestamps
+
+    Tocantins will very likely not observe DST starting this spring.
+    (Thanks to Steffen Thorsen.)
+
+    Jordan will likely stay at UT +03 indefinitely, and will not fall
+    back this fall.
+
+    Palestine will fall back at 00:00, not 01:00.  (Thanks to Steffen Thorsen.)
+
+  Changes affecting API
+
+    The types of the global variables 'timezone' and 'altzone' (if present)
+    have been changed back to 'long'.  This is required for 'timezone'
+    by POSIX, and for 'altzone' by common practice, e.g., Solaris 11.
+    These variables were originally 'long' in the tz code, but were
+    mistakenly changed to 'time_t' in 1987; nobody reported the
+    incompatibility until now.  The difference matters on x32, where
+    'long' is 32 bits and 'time_t' is 64.  (Thanks to Elliott Hughes.)
+
+  Changes affecting the build procedure
+
+    Avoid long strings in leapseconds.awk to work around a mawk bug.
+    (Thanks to Cyril Baurand.)
+
+  Changes affecting documentation and commentary
+
+    New file 'NEWS' that contains release notes like this one.
+
+    Paraguay's law does not specify DST transition time; 00:00 is customary.
+    (Thanks to Waldemar Villamayor-Venialbo.)
+
+    Minor capitalization fixes.
+
+  Changes affecting version-control only
+
+    The experimental GitHub repository now contains annotated and
+    signed tags for recent releases, e.g., '2013e' for Release 2013e.
+    Releases are tagged starting with 2012e; earlier releases were
+    done differently, and tags would either not have a simple name or
+    not exactly match what was released.
+
+    'make set-timestamps' is now simpler and a bit more portable.
+
+
+Release 2013e - 2013-09-19 23:50:04 -0700
+
+  Changes affecting near-future timestamps
+
+    This year Fiji will start DST on October 27, not October 20.
+    (Thanks to David Wheeler for the heads-up.)  For now, guess that
+    Fiji will continue to spring forward the Sunday before the fourth
+    Monday in October.
+
+  Changes affecting current and future time zone abbreviations
+
+    Use WIB/WITA/WIT rather than WIT/CIT/EIT for alphabetic Indonesian
+    time zone abbreviations since 1932.  (Thanks to George Ziegler,
+    Priyadi Iman Nurcahyo, Zakaria, Jason Grimes, Martin Pitt, and
+    Benny Lin.)  This affects Asia/Dili, Asia/Jakarta, Asia/Jayapura,
+    Asia/Makassar, and Asia/Pontianak.
+
+    Use ART (UT -03, standard time), rather than WARST (also -03, but
+    daylight saving time) for San Luis, Argentina since 2009.
+
+  Changes affecting Godthåb timestamps after 2037 if version mismatch
+
+    Allow POSIX-like TZ strings where the transition time's hour can
+    range from -167 through 167, instead of the POSIX-required 0
+    through 24.  E.g., TZ='FJT-12FJST,M10.3.1/146,M1.3.4/75' for the
+    new Fiji rules.  This is a more-compact way to represent
+    far-future timestamps for America/Godthab, America/Santiago,
+    Antarctica/Palmer, Asia/Gaza, Asia/Hebron, Asia/Jerusalem,
+    Pacific/Easter, and Pacific/Fiji.  Other zones are unaffected by
+    this change.  (Derived from a suggestion by Arthur David Olson.)
+
+    Allow POSIX-like TZ strings where daylight saving time is in
+    effect all year.  E.g., TZ='WART4WARST,J1/0,J365/25' for Western
+    Argentina Summer Time all year.  This supports a more-compact way
+    to represent the 2013d data for America/Argentina/San_Luis.
+    Because of the change for San Luis noted above this change does not
+    affect the current data.  (Thanks to Andrew Main (Zefram) for
+    suggestions that improved this change.)
+
+    Where these two TZ changes take effect, there is a minor extension
+    to the tz file format in that it allows new values for the
+    embedded TZ-format string, and the tz file format version number
+    has therefore been increased from 2 to 3 as a precaution.
+    Version-2-based client code should continue to work as before for
+    all timestamps before 2038.  Existing version-2-based client code
+    (tzcode, GNU/Linux, Solaris) has been tested on version-3-format
+    files, and typically works in practice even for timestamps after
+    2037; the only known exception is America/Godthab.
+
+  Changes affecting timestamps before 1970
+
+    Pacific/Johnston is now a link to Pacific/Honolulu.  This corrects
+    some errors before 1947.
+
+    Some zones have been turned into links, when they differ from existing
+    zones only in older data entries that were likely invented or that
+    differ only in LMT or transitions from LMT.  These changes affect
+    only timestamps before 1943.  The affected zones are:
+    Africa/Juba, America/Anguilla, America/Aruba, America/Dominica,
+    America/Grenada, America/Guadeloupe, America/Marigot,
+    America/Montserrat, America/St_Barthelemy, America/St_Kitts,
+    America/St_Lucia, America/St_Thomas, America/St_Vincent,
+    America/Tortola, and Europe/Vaduz.  (Thanks to Alois Treindl for
+    confirming that the old Europe/Vaduz zone was wrong and the new
+    link is better for WWII-era times.)
+
+    Change Kingston Mean Time from -5:07:12 to -5:07:11.  This affects
+    America/Cayman, America/Jamaica and America/Grand_Turk timestamps
+    from 1890 to 1912.
+
+    Change the UT offset of Bern Mean Time from 0:29:44 to 0:29:46.
+    This affects Europe/Zurich timestamps from 1853 to 1894.  (Thanks
+    to Alois Treindl.)
+
+    Change the date of the circa-1850 Zurich transition from 1849-09-12
+    to 1853-07-16, overriding Shanks with data from Messerli about
+    postal and telegraph time in Switzerland.
+
+  Changes affecting time zone abbreviations before 1970
+
+    For Asia/Jakarta, use BMT (not JMT) for mean time from 1923 to 1932,
+    as Jakarta was called Batavia back then.
+
+  Changes affecting API
+
+    The 'zic' command now outputs a dummy transition when far-future
+    data can't be summarized using a TZ string, and uses a 402-year
+    window rather than a 400-year window.  For the current data, this
+    affects only the Asia/Tehran file.  It does not affect any of the
+    timestamps that this file represents, so zdump outputs the same
+    information as before.  (Thanks to Andrew Main (Zefram).)
+
+    The 'date' command has a new '-r' option, which lets you specify
+    the integer time to display, a la FreeBSD.
+
+    The 'tzselect' command has two new options '-c' and '-n', which lets you
+    select a zone based on latitude and longitude.
+
+    The 'zic' command's '-v' option now warns about constructs that
+    require the new version-3 binary file format.  (Thanks to Arthur
+    David Olson for the suggestion.)
+
+    Support for floating-point time_t has been removed.
+    It was always dicey, and POSIX no longer requires it.
+    (Thanks to Eric Blake for suggesting to the POSIX committee to
+    remove it, and thanks to Alan Barrett, Clive D.W. Feather, Andy
+    Heninger, Arthur David Olson, and Alois Treindl, for reporting
+    bugs and elucidating some of the corners of the old floating-point
+    implementation.)
+
+    The signatures of 'offtime', 'timeoff', and 'gtime' have been
+    changed back to the old practice of using 'long' to represent UT
+    offsets.  This had been inadvertently and mistakenly changed to
+    'int_fast32_t'.  (Thanks to Christos Zoulas.)
+
+    The code avoids undefined behavior on integer overflow in some
+    more places, including gmtime, localtime, mktime and zdump.
+
+  Changes affecting the zdump utility
+
+    zdump now outputs "UT" when referring to Universal Time, not "UTC".
+    "UTC" does not make sense for timestamps that predate the introduction
+    of UTC, whereas "UT", a more-generic term, does.  (Thanks to Steve Allen
+    for clarifying UT vs UTC.)
+
+  Data changes affecting behavior of tzselect and similar programs
+
+    Country code BQ is now called the more-common name "Caribbean Netherlands"
+    rather than the more-official "Bonaire, St Eustatius & Saba".
+
+    Remove from zone.tab the names America/Montreal, America/Shiprock,
+    and Antarctica/South_Pole, as they are equivalent to existing
+    same-country-code zones for post-1970 timestamps.  The data entries for
+    these names are unchanged, so the names continue to work as before.
+
+  Changes affecting code internals
+
+    zic -c now runs way faster on 64-bit hosts when given large numbers.
+
+    zic now uses vfprintf to avoid allocating and freeing some memory.
+
+    tzselect now computes the list of continents from the data,
+    rather than have it hard-coded.
+
+    Minor changes pacify GCC 4.7.3 and GCC 4.8.1.
+
+  Changes affecting the build procedure
+
+    The 'leapseconds' file is now generated automatically from a
+    new file 'leap-seconds.list', which is a copy of
+    <ftp://ftp.nist.gov/pub/time/leap-seconds.list>
+    A new source file 'leapseconds.awk' implements this.
+    The goal is simplification of the future maintenance of 'leapseconds'.
+
+    When building the 'posix' or 'right' subdirectories, if the
+    subdirectory would be a copy of the default subdirectory, it is
+    now made a symbolic link if that is supported.  This saves about
+    2 MB of file system space.
+
+    The links America/Shiprock and Antarctica/South_Pole have been
+    moved to the 'backward' file.  This affects only nondefault builds
+    that omit 'backward'.
+
+  Changes affecting version-control only
+
+    .gitignore now ignores 'date'.
+
+  Changes affecting documentation and commentary
+
+    Changes to the 'tzfile' man page
+
+      It now mentions that the binary file format may be extended in
+      future versions by appending data.
+
+      It now refers to the 'zdump' and 'zic' man pages.
+
+    Changes to the 'zic' man page
+
+      It lists conditions that elicit a warning with '-v'.
+
+      It says that the behavior is unspecified when duplicate names
+      are given, or if the source of one link is the target of another.
+
+      Its examples are updated to match the latest data.
+
+      The definition of white space has been clarified slightly.
+      (Thanks to Michael Deckers.)
+
+    Changes to the 'Theory' file
+
+      There is a new section about the accuracy of the tz database,
+      describing the many ways that errors can creep in, and
+      explaining why so many of the pre-1970 timestamps are wrong or
+      misleading (thanks to Steve Allen, Lester Caine, and Garrett
+      Wollman for discussions that contributed to this).
+
+      The 'Theory' file describes LMT better (this follows a
+      suggestion by Guy Harris).
+
+      It refers to the 2013 edition of POSIX rather than the 2004 edition.
+
+      It's mentioned that excluding 'backward' should not affect the
+      other data, and it suggests at least one zone.tab name per
+      inhabited country (thanks to Stephen Colebourne).
+
+      Some longstanding restrictions on names are documented, e.g.,
+      'America/New_York' precludes 'America/New_York/Bronx'.
+
+      It gives more reasons for the 1970 cutoff.
+
+      It now mentions which time_t variants are supported, such as
+      signed integer time_t.  (Thanks to Paul Goyette for reporting
+      typos in an experimental version of this change.)
+
+      (Thanks to Philip Newton for correcting typos in these changes.)
+
+    Documentation and commentary is more careful to distinguish UT in
+    general from UTC in particular.  (Thanks to Steve Allen.)
+
+    Add a better source for the Zurich 1894 transition.
+    (Thanks to Pierre-Yves Berger.)
+
+    Update shapefile citations in tz-link.htm.  (Thanks to Guy Harris.)
+
+
+Release 2013d - 2013-07-05 07:38:01 -0700
+
+  Changes affecting future timestamps:
+
+    Morocco's midsummer transitions this year are July 7 and August 10,
+    not July 9 and August 8.  (Thanks to Andrew Paprocki.)
+
+    Israel now falls back on the last Sunday of October.
+    (Thanks to Ephraim Silverberg.)
+
+  Changes affecting past timestamps:
+
+    Specify Jerusalem's location more precisely; this changes the pre-1880
+    times by 2 s.
+
+  Changing affecting metadata only:
+
+    Fix typos in the entries for country codes BQ and SX.
+
+  Changes affecting code:
+
+    Rework the code to fix a bug with handling Australia/Macquarie on
+    32-bit hosts (thanks to Arthur David Olson).
+
+    Port to platforms like NetBSD, where time_t can be wider than long.
+
+    Add support for testing time_t types other than the system's.
+    Run 'make check_time_t_alternatives' to try this out.
+    Currently, the tests fail for unsigned time_t;
+    this should get fixed at some point.
+
+  Changes affecting documentation and commentary:
+
+    Deemphasize the significance of national borders.
+
+    Update the zdump man page.
+
+    Remove obsolete NOID comment (thanks to Denis Excoffier).
+
+    Update several URLs and comments in the web pages.
+
+    Spelling fixes (thanks to Kevin Lyda and Jonathan Leffler).
+
+    Update URL for CLDR Zone->Tzid table (thanks to Yoshito Umaoka).
+
+
+Release 2013c - 2013-04-19 16:17:40 -0700
+
+  Changes affecting current and future timestamps:
+
+    Palestine observed DST starting March 29, 2013.  (Thanks to
+    Steffen Thorsen.)  From 2013 on, Gaza and Hebron both observe DST,
+    with the predicted rules being the last Thursday in March at 24:00
+    to the first Friday on or after September 21 at 01:00.
+
+    Assume that the recent change to Paraguay's DST rules is permanent,
+    by moving the end of DST to the 4th Sunday in March every year.
+    (Thanks to Carlos Raúl Perasso.)
+
+  Changes affecting past timestamps:
+
+    Fix some historical data for Palestine to agree with that of
+    timeanddate.com, as follows:
+
+	  The spring 2008 change in Gaza and Hebron was on 00:00 Mar 28, not
+	  00:00 Apr 1.
+
+	  The fall 2009 change in Gaza and Hebron on Sep 4 was at 01:00, not
+	  02:00.
+
+	  The spring 2010 change in Hebron was 00:00 Mar 26, not 00:01 Mar 27.
+
+	  The spring 2011 change in Gaza was 00:01 Apr 1, not 12:01 Apr 2.
+
+	  The spring 2011 change in Hebron on Apr 1 was at 00:01, not 12:01.
+
+	  The fall 2011 change in Hebron on Sep 30 was at 00:00, not 03:00.
+
+    Fix times of habitation for Macquarie to agree with the Tasmania
+    Parks & Wildlife Service history, which indicates that permanent
+    habitation was 1899-1919 and 1948 on.
+
+  Changing affecting metadata only:
+
+    Macquarie Island is politically part of Australia, not Antarctica.
+    (Thanks to Tobias Conradi.)
+
+    Sort Macquarie more-consistently with other parts of Australia.
+    (Thanks to Tim Parenti.)
+
+
+Release 2013b - 2013-03-10 22:33:40 -0700
+
+  Changes affecting current and future timestamps:
+
+    Haiti uses US daylight-saving rules this year, and presumably future years.
+    This changes timestamps starting today.  (Thanks to Steffen Thorsen.)
+
+    Paraguay will end DST on March 24 this year.
+    (Thanks to Steffen Thorsen.)  For now, assume it's just this year.
+
+    Morocco does not observe DST during Ramadan;
+    try to predict Ramadan in Morocco as best we can.
+    (Thanks to Erik Homoet for the heads-up.)
+
+  Changes affecting commentary:
+
+    Update URLs in tz-link page.  Add URLs for webOS, BB10, iOS.
+    Update URL for Solaris.  Mention Internet RFC 6557.
+    Update Internet RFCs 2445->5545, 2822->5322.
+    Switch from FTP to HTTP for Internet RFCs.
+
+
+Release 2013a - 2013-02-27 09:20:35 -0800
+
+  Change affecting binary data format:
+
+    The zone offset at the end of version-2-format zone files is now
+    allowed to be 24:00, as per POSIX.1-2008.  (Thanks to Arthur David Olson.)
+
+  Changes affecting current and future timestamps:
+
+    Chile's 2013 rules, and we guess rules for 2014 and later, will be
+    the same as 2012, namely Apr Sun>=23 03:00 UTC to Sep Sun>=2 04:00 UTC.
+    (Thanks to Steffen Thorsen and Robert Elz.)
+
+    New Zones Asia/Khandyga, Asia/Ust-Nera, Europe/Busingen.
+    (Thanks to Tobias Conradi and Arthur David Olson.)
+
+  Many changes affect historical timestamps before 1940.
+  These were deduced from: Milne J. Civil time. Geogr J. 1899
+  Feb;13(2):173-94 <https://www.jstor.org/stable/1774359>.
+
+  Changes affecting the code:
+
+    Fix zic bug that mishandled Egypt's 2010 changes (this also affected
+    the data).  (Thanks to Arthur David Olson.)
+
+    Fix localtime bug when time_t is unsigned and data files were generated
+    by a signed time_t system.  (Thanks to Doug Bailey for reporting and
+    to Arthur David Olson for fixing.)
+
+    Allow the email address for bug reports to be set by the packager.
+    The default is tz@iana.org, as before.  (Thanks to Joseph S. Myers.)
+
+    Update HTML checking to be compatible with Ubuntu 12.10.
+
+    Check that files are a safe subset of ASCII.  At some point we may
+    relax this requirement to a safe subset of UTF-8.  Without the
+    check, some non-UTF-8 encodings were leaking into the distribution.
+
+  Commentary changes:
+
+    Restore a comment about copyright notices that was inadvertently deleted.
+    (Thanks to Arthur David Olson.)
+
+    Improve the commentary about which districts observe what times
+    in Russia.  (Thanks to Oscar van Vlijmen and Arthur David Olson.)
+
+    Add web page links to tz.js.
+
+    Add "Run by the Monkeys" to tz-art.  (Thanks to Arthur David Olson.)
+
+
+Release 2012j - 2012-11-12 18:34:49 -0800
+
+  Libya moved to CET this weekend, but with DST planned next year.
+  (Thanks to Even Scharning, Steffen Thorsen, and Tim Parenti.)
+
+  Signatures now have the extension .asc, not .sign, as that's more
+  standard.  (Thanks to Phil Pennock.)
+
+  The output of 'zdump --version', and of 'zic --version', now
+  uses a format that is more typical for --version.
+  (Thanks to Joseph S. Myers.)
+
+  The output of 'tzselect --help', 'zdump --help', and 'zic --help'
+  now uses tz@iana.org rather than the old elsie address.
+
+  zic -v now complains about abbreviations that are less than 3
+  or more than 6 characters, as per Posix.  Formerly, it checked
+  for abbreviations that were more than 3.
+
+  'make public' no longer puts its temporary directory under /tmp,
+  and uses the just-built zic rather than the system zic.
+
+  Various fixes to documentation and commentary.
+
+
+Release 2012i - 2012-11-03 12:57:09 -0700
+
+  Cuba switches from DST tomorrow at 01:00.  (Thanks to Steffen Thorsen.)
+
+  Linker flags can now be specified via LDFLAGS.
+  AWK now defaults to 'awk', not 'nawk'.
+  The shell in tzselect now defaults to /bin/bash, but this can
+  be overridden by specifying KSHELL.
+  The main web page now mentions the unofficial GitHub repository.
+  (Thanks to Mike Frysinger.)
+
+  Tarball signatures can now be built by running 'make signatures'.
+  There are also new makefile rules 'tarballs', 'check_public', and
+  separate makefile rules for each tarball and signature file.
+  A few makefile rules are now more portable to strict POSIX.
+
+  The main web page now lists the canonical IANA URL.
+
+
+Release 2012h - 2012-10-26 22:49:10 -0700
+
+  Bahia no longer has DST.  (Thanks to Kelley Cook.)
+
+  Tocantins has DST.  (Thanks to Rodrigo Severo.)
+
+  Israel has new DST rules next year.  (Thanks to Ephraim Silverberg.)
+
+  Jordan stays on DST this winter.  (Thanks to Steffen Thorsen.)
+
+  Web page updates.
+
+  More C modernization, except that at Arthur David Olson's suggestion
+  the instances of 'register' were kept.
+
+
+Release 2012g - 2012-10-17 20:59:45 -0700
+
+  Samoa fall 2012 and later.  (Thanks to Nicholas Pereira and Robert Elz.)
+
+  Palestine fall 2012.  (Thanks to Steffen Thorsen.)
+
+  Assume C89.
+
+  To attack the version-number problem, this release ships the file
+  'Makefile' (which contains the release number) in both the tzcode and
+  the tzdata tarballs.  The two Makefiles are identical, and should be
+  identical in any matching pair of tarballs, so it shouldn't matter
+  which order you extract the tarballs.  Perhaps we can come up with a
+  better version-number scheme at some point; this scheme does have the
+  virtue of not adding more files.
+
+
+Release 2012f - 2012-09-12 23:17:03 -0700
+
+  * australasia (Pacific/Fiji): Fiji DST is October 21 through January
+    20 this year.  (Thanks to Steffen Thorsen.)
+
+
+Release 2012e - 2012-08-02 20:44:55 -0700
+
+  * australasia (Pacific/Fakaofo): Tokelau is UT +13, not +14.
+    (Thanks to Steffen Thorsen.)
+
+  * Use a single version number for both code and data.
+
+  * .gitignore: New file.
+
+  * Remove trailing white space.
+
+
+Release code2012c-data2012d - 2012-07-19 16:35:33 -0700
+
+  Changes for Morocco's timestamps, which take effect in a couple of
+  hours, along with infrastructure changes to accommodate how the tz
+  code and data are released on IANA.
+
+
+Release data2012c - 2012-03-27 12:17:25 -0400
+
+  africa
+	Summer time changes for Morocco (to start late April 2012)
+
+  asia
+	Changes for 2012 for Gaza & the West Bank (Hebron) and Syria
+
+  northamerica
+	Haiti following US/Canada rules for 2012 (and we're assuming,
+	for now anyway, for the future).
+
+
+Release 2012b - 2012-03-02 12:29:15 +0700
+
+  There is just one change to tzcode2012b (compared with 2012a):
+  the Makefile that was accidentally included with 2012a has been
+  replaced with the version that should have been there, which is
+  identical with the previous version (from tzcode2011i).
+
+  There are just two changes in tzdata2012b compared with 2012a.
+
+  Most significantly, summer time in Cuba has been delayed 3 weeks
+  (now starts April 1 rather than March 11).   Since Mar 11 (the old start
+  date, as listed in 2012a) is just a little over a week away, this
+  change is urgent.
+
+  Less importantly, an excess tab in one of the changes in zone.tab
+  in 2012a has been removed.
+
+
+Release 2012a - 2012-03-01 18:28:10 +0700
+
+  The changes in tzcode2012a (compared to the previous version, 2011i)
+  are entirely to the README and tz-art.htm and tz-link.htm files, if
+  none of those concern you, you can ignore the code update.  The changes
+  reflect the changed addresses for the mailing list and the code and
+  data distribution points & methods (and a link to DateTime::TimeZone::Tzfile
+  has been added to tz-link.htm).
+
+  In tzdata2012a (compared to the previous release, which was 2011n)
+  the major changes are:
+	Chile 2011/2012 and 2012/2013 summer time date adjustments.
+	Falkland Islands onto permanent summer time (we're assuming for the
+		foreseeable future, though 2012 is all we're fairly certain of.)
+	Armenia has abolished Summer Time.
+	Tokelau jumped the International Date Line back last December
+		(just the same as their near neighbour, Samoa).
+	America/Creston is a new zone for a small area of British Columbia
+	There will be a leapsecond 2012-06-30 23:59:60 UTC.
+
+  Other minor changes are:
+	Corrections to 1918 Canadian summer time end dates.
+	Updated URL for UK time zone history (in comments)
+	A few typos in Le Corre's list of free French place names (comments)
+
+
+Release data2011n - 2011-10-30 14:57:54 +0700
+
+  There are three changes of note - most urgently, Cuba (America/Havana)
+  has extended summer time by two weeks, now to end on Nov 13, rather than
+  the (already past) Oct 30.   Second, the Pridnestrovian Moldavian Republic
+  (Europe/Tiraspol) decided not to split from the rest of Moldova after
+  all, and consequently that zone has been removed (again) and reinstated
+  in the "backward" file as a link to Europe/Chisinau.   And third, the
+  end date for Fiji's summer time this summer was moved forward from the
+  earlier planned Feb 26, to Jan 22.
+
+  Apart from that, Moldova (MD) returns to a single entry in zone.tab
+  (and the incorrect syntax that was in the 2011m version of that file
+  is so fixed - it would have been fixed in a different way had this
+  change not happened - that's the "missing" sccs version id).
+
+
+Release data2011m - 2011-10-24 21:42:16 +0700
+
+  In particular, the typos in comments in the data (2011-11-17 should have
+  been 2011-10-17 as Alan Barrett noted, and spelling of Tiraspol that
+  Tim Parenti noted) have been fixed, and the change for Ukraine has been
+  made in all 4 Ukrainian zones, rather than just Kiev (again, thanks to
+  Tim Parenti, and also Denys Gavrysh)
+
+  In addition, I added Europe/Tiraspol to zone.tab.
+
+  This time, all the files have new version numbers...  (including the files
+  otherwise unchanged in 2011m that were changed in 2011l but didn't get new
+  version numbers there...)
+
+
+Release data2011l - 2011-10-10 11:15:43 +0700
+
+  There are just 2 changes that cause different generated tzdata files from
+  zic, to Asia/Hebron and Pacific/Fiji - the possible change for Bahia, Brazil
+  is included, but commented out.  Compared with the diff I sent out last week,
+  this version also includes attributions for the sources for the changes
+  (in much the same format as ado used, but the html tags have not been
+  checked, verified, or used in any way at all, so if there are errors there,
+  please let me know.)
+
+
+Release data2011k - 2011-09-20 17:54:03 -0400
+
+  [not summarized]
+
+
+Release data2011j - 2011-09-12 09:22:49 -0400
+
+  (contemporary changes for Samoa; past changes for Kenya, Uganda, and
+  Tanzania); there are also two spelling corrections to comments in
+  the australasia file (with thanks to Christos Zoulas).
+
+
+Release 2011i - 2011-08-29 05:56:32 -0400
+
+  [not summarized]
+
+
+Release data2011h - 2011-06-15 18:41:48 -0400
+
+  Russia and Curaçao changes
+
+
+Release 2011g - 2011-04-25 09:07:22 -0400
+
+  update the rules for Egypt to reflect its abandonment of DST this year
+
+
+Release 2011f - 2011-04-06 17:14:53 -0400
+
+  [not summarized]
+
+
+Release 2011e - 2011-03-31 16:04:38 -0400
+
+  Morocco, Chile, and tz-link changes
+
+
+Release 2011d - 2011-03-14 09:18:01 -0400
+
+  changes that impact present-day timestamps in Cuba, Samoa, and Turkey
+
+
+Release 2011c - 2011-03-07 09:30:09 -0500
+
+  These do affect current timestamps in Chile and Annette Island, Canada.
+
+
+Release 2011b - 2011-02-07 08:44:50 -0500
+
+  [not summarized]
+
+
+Release 2011a - 2011-01-24 10:30:16 -0500
+
+  [not summarized]
+
+
+Release data2010o - 2010-11-01 09:18:23 -0400
+
+  change to the end of DST in Fiji in 2011
+
+
+Release 2010n - 2010-10-25 08:19:17 -0400
+
+  [not summarized]
+
+
+Release 2010m - 2010-09-27 09:24:48 -0400
+
+  Hong Kong, Vostok, and zic.c changes
+
+
+Release 2010l - 2010-08-16 06:57:25 -0400
+
+  [not summarized]
+
+
+Release 2010k - 2010-07-26 10:42:27 -0400
+
+  [not summarized]
+
+
+Release 2010j - 2010-05-10 09:07:48 -0400
+
+  changes for Bahía de Banderas and for version naming
+
+
+Release data2010i - 2010-04-16 18:50:45 -0400
+
+  the end of DST in Morocco on 2010-08-08
+
+
+Release data2010h - 2010-04-05 09:58:56 -0400
+
+  [not summarized]
+
+
+Release data2010g - 2010-03-24 11:14:53 -0400
+
+  [not summarized]
+
+
+Release 2010f - 2010-03-22 09:45:46 -0400
+
+  [not summarized]
+
+
+Release data2010e - 2010-03-08 14:24:27 -0500
+
+  corrects the Dhaka bug found by Danvin Ruangchan
+
+
+Release data2010d - 2010-03-06 07:26:01 -0500
+
+  [not summarized]
+
+
+Release 2010c - 2010-03-01 09:20:58 -0500
+
+  changes including KRE's suggestion for earlier initialization of
+  "goahead" and "goback" structure elements
+
+
+Release code2010a - 2010-02-16 10:40:04 -0500
+
+  [not summarized]
+
+
+Release data2010b - 2010-01-20 12:37:01 -0500
+
+  Mexico changes
+
+
+Release data2010a - 2010-01-18 08:30:04 -0500
+
+  changes to Dhaka
+
+
+Release data2009u - 2009-12-26 08:32:28 -0500
+
+  changes to DST in Bangladesh
+
+
+Release 2009t - 2009-12-21 13:24:27 -0500
+
+  [not summarized]
+
+
+Release data2009s - 2009-11-14 10:26:32 -0500
+
+  (cosmetic) Antarctica change and the DST-in-Fiji-in-2009-and-2010 change
+
+
+Release 2009r - 2009-11-09 10:10:31 -0500
+
+  "antarctica" and "tz-link.htm" changes
+
+
+Release 2009q - 2009-11-02 09:12:40 -0500
+
+  with two corrections as reported by Eric Muller and Philip Newton
+
+
+Release data2009p - 2009-10-23 15:05:27 -0400
+
+  Argentina (including San Luis) changes (with the correction from
+  Mariano Absatz)
+
+
+Release data2009o - 2009-10-14 16:49:38 -0400
+
+  Samoa (commentary only), Pakistan, and Bangladesh changes
+
+
+Release data2009n - 2009-09-22 15:13:38 -0400
+
+  added commentary for Argentina and a change to the end of DST in
+  2009 in Pakistan
+
+
+Release data2009m - 2009-09-03 10:23:43 -0400
+
+  Samoa and Palestine changes
+
+
+Release data2009l - 2009-08-14 09:13:07 -0400
+
+  Samoa (comments only) and Egypt
+
+
+Release 2009k - 2009-07-20 09:46:08 -0400
+
+  [not summarized]
+
+
+Release data2009j - 2009-06-15 06:43:59 -0400
+
+  Bangladesh change (with a short turnaround since the DST change is
+  impending)
+
+
+Release 2009i - 2009-06-08 09:21:22 -0400
+
+  updating for DST in Bangladesh this year
+
+
+Release 2009h - 2009-05-26 09:19:14 -0400
+
+  [not summarized]
+
+
+Release data2009g - 2009-04-20 16:34:07 -0400
+
+  Cairo
+
+
+Release data2009f - 2009-04-10 11:00:52 -0400
+
+  correct DST in Pakistan
+
+
+Release 2009e - 2009-04-06 09:08:11 -0400
+
+  [not summarized]
+
+
+Release 2009d - 2009-03-23 09:38:12 -0400
+
+  Morocco, Tunisia, Argentina, and American Astronomical Society changes
+
+
+Release data2009c - 2009-03-16 09:47:51 -0400
+
+  change to the start of Cuban DST
+
+
+Release 2009b - 2009-02-09 11:15:22 -0500
+
+  [not summarized]
+
+
+Release 2009a - 2009-01-21 10:09:39 -0500
+
+  [not summarized]
+
+
+Release data2008i - 2008-10-21 12:10:25 -0400
+
+  southamerica and zone.tab files, with Argentina DST rule changes and
+  United States zone reordering and recommenting
+
+
+Release 2008h - 2008-10-13 07:33:56 -0400
+
+  [not summarized]
+
+
+Release 2008g - 2008-10-06 09:03:18 -0400
+
+  Fix a broken HTML anchor and update Brazil's DST transitions;
+  there's also a slight reordering of information in tz-art.htm.
+
+
+Release data2008f - 2008-09-09 22:33:26 -0400
+
+  [not summarized]
+
+
+Release 2008e - 2008-07-28 14:11:17 -0400
+
+  changes by Arthur David Olson and Jesper Nørgaard Welen
+
+
+Release data2008d - 2008-07-07 09:51:38 -0400
+
+  changes by Arthur David Olson, Paul Eggert, and Rodrigo Severo
+
+
+Release data2008c - 2008-05-19 17:48:03 -0400
+
+  Pakistan, Morocco, and Mongolia
+
+
+Release data2008b - 2008-03-24 08:30:59 -0400
+
+  including renaming Asia/Calcutta to Asia/Kolkata, with a backward
+  link provided
+
+
+Release 2008a - 2008-03-08 05:42:16 -0500
+
+  [not summarized]
+
+
+Release 2007k - 2007-12-31 10:25:22 -0500
+
+  most importantly, changes to the "southamerica" file based on
+  Argentina's readoption of daylight saving time
+
+
+Release 2007j - 2007-12-03 09:51:01 -0500
+
+  1. eliminate the "P" (parameter) macro;
+
+  2. the "noncontroversial" changes circulated on the time zone
+  mailing list (less the changes to "logwtmp.c");
+
+  3. eliminate "too many transition" errors when "min" is used in time
+  zone rules;
+
+  4. changes by Paul Eggert (including updated information for Venezuela).
+
+
+Release data2007i - 2007-10-30 10:28:11 -0400
+
+  changes for Cuba and Syria
+
+
+Release 2007h - 2007-10-01 10:05:51 -0400
+
+  changes by Paul Eggert, as well as an updated link to the ICU
+  project in tz-link.htm
+
+
+Release 2007g - 2007-08-20 10:47:59 -0400
+
+  changes by Paul Eggert
+
+  The "leapseconds" file has been updated to incorporate the most
+  recent International Earth Rotation and Reference Systems Service
+  (IERS) bulletin.
+
+  There's an addition to tz-art.htm regarding the television show "Medium".
+
+
+Release 2007f - 2007-05-07 10:46:46 -0400
+
+  changes by Paul Eggert (including Haiti, Turks and Caicos, and New
+  Zealand)
+
+  changes to zic.c to allow hour values greater than 24 (along with
+  Paul's improved time value overflow checking)
+
+
+Release 2007e - 2007-04-02 10:11:52 -0400
+
+  Syria and Honduras changes by Paul Eggert
+
+  zic.c variable renaming changes by Arthur David Olson
+
+
+Release 2007d - 2007-03-20 08:48:30 -0400
+
+  changes by Paul Eggert
+
+  the elimination of white space at the ends of lines
+
+
+Release 2007c - 2007-02-26 09:09:37 -0500
+
+  changes by Paul Eggert
+
+
+Release 2007b - 2007-02-12 09:34:20 -0500
+
+  Paul Eggert's proposed change to the quotation handling logic in zic.c.
+
+  changes to the commentary in "leapseconds" reflecting the IERS
+  announcement that there is to be no positive leap second at the end
+  of June 2007.
+
+
+Release 2007a - 2007-01-08 12:28:29 -0500
+
+  changes by Paul Eggert
+
+  Derick Rethans's Asmara change
+
+  Oscar van Vlijmen's Easter Island local mean time change
+
+  symbolic link changes
+
+
+Release 2006p - 2006-11-27 08:54:27 -0500
+
+  changes by Paul Eggert
+
+
+Release 2006o - 2006-11-06 09:18:07 -0500
+
+  changes by Paul Eggert
+
+
+Release 2006n - 2006-10-10 11:32:06 -0400
+
+  changes by Paul Eggert
+
+
+Release 2006m - 2006-10-02 15:32:35 -0400
+
+  changes for Uruguay, Palestine, and Egypt by Paul Eggert
+
+  (minimalist) changes to zic.8 to clarify "until" information
+
+
+Release data2006l - 2006-09-18 12:58:11 -0400
+
+  Paul's best-effort work on this coming weekend's Egypt time change
+
+
+Release 2006k - 2006-08-28 12:19:09 -0400
+
+  changes by Paul Eggert
+
+
+Release 2006j - 2006-08-21 09:56:32 -0400
+
+  changes by Paul Eggert
+
+
+Release code2006i - 2006-08-07 12:30:55 -0400
+
+  localtime.c fixes
+
+  Ken Pizzini's conversion script
+
+
+Release code2006h - 2006-07-24 09:19:37 -0400
+
+  adds public domain notices to four files
+
+  includes a fix for transition times being off by a second
+
+  adds a new recording to the "arts" file (information courtesy Colin Bowern)
+
+
+Release 2006g - 2006-05-08 17:18:09 -0400
+
+  northamerica changes by Paul Eggert
+
+
+Release 2006f - 2006-05-01 11:46:00 -0400
+
+  a missing version number problem is fixed (with thanks to Bradley
+  White for catching the problem)
+
+
+Release 2006d - 2006-04-17 14:33:43 -0400
+
+  changes by Paul Eggert
+
+  added new items to tz-arts.htm that were found by Paul
+
+
+Release 2006c - 2006-04-03 10:09:32 -0400
+
+  two sets of data changes by Paul Eggert
+
+  a fencepost error fix in zic.c
+
+  changes to zic.c and the "europe" file to minimize differences
+  between output produced by the old 32-bit zic and the new 64-bit
+  version
+
+
+Release 2006b - 2006-02-20 10:08:18 -0500
+  [tz32code2006b + tz64code2006b + tzdata2006b]
+
+  64-bit code
+
+  All SCCS IDs were bumped to "8.1" for this release.
+
+
+Release 2006a - 2006-01-30 08:59:31 -0500
+
+  changes by Paul Eggert (in particular, Indiana time zone moves)
+
+  an addition to the zic manual page to describe how special-case
+  transitions are handled
+
+
+Release 2005r - 2005-12-27 09:27:13 -0500
+
+  Canadian changes by Paul Eggert
+
+  They also add "<pre>" directives to time zone data files and reflect
+  changes to warning message logic in "zdump.c" (but with calls to
+  "gettext" kept unbundled at the suggestion of Ken Pizzini).
+
+
+Release 2005q - 2005-12-13 09:17:09 -0500
+
+  Nothing earth-shaking here:
+	1.  Electronic mail addresses have been removed.
+	2.  Casts of the return value of exit have been removed.
+	3.  Casts of the argument of is.* macros have been added.
+	4.  Indentation in one section of zic.c has been fixed.
+	5.  References to dead URLs in the data files have been dealt with.
+
+
+Release 2005p - 2005-12-05 10:30:53 -0500
+
+  "systemv", "tz-link.htm", and "zdump.c" changes
+  (less the casts of arguments to the is* macros)
+
+
+Release 2005o - 2005-11-28 10:55:26 -0500
+
+  Georgia, Cuba, Nicaragua, and Jordan changes by Paul Eggert
+
+  zdump.c lint fixes by Arthur David Olson
+
+
+Release 2005n - 2005-10-03 09:44:09 -0400
+
+  changes by Paul Eggert (both the Uruguay changes and the Kyrgyzstan
+  et al. changes)
+
+
+Release 2005m - 2005-08-29 12:15:40 -0400
+
+  changes by Paul Eggert (with a small tweak to the tz-art change)
+
+  a declaration of an unused variable has been removed from zdump.c
+
+
+Release 2005l - 2005-08-22 12:06:39 -0400
+
+  changes by Paul Eggert
+
+  overflow/underflow checks by Arthur David Olson, minus changes to
+  the "Theory" file about the pending addition of 64-bit data (I grow
+  less confident of the changes being accepted with each passing day,
+  and the changes no longer increase the data files nine-fold--there's
+  less than a doubling in size by my local Sun's reckoning)
+
+
+Release 2005k - 2005-07-14 14:14:24 -0400
+
+  The "leapseconds" file has been edited to reflect the recently
+  announced leap second at the end of 2005.
+
+  I've also deleted electronic mail addresses from the files as an
+  anti-spam measure.
+
+
+Release 2005j - 2005-06-13 14:34:13 -0400
+
+  These reflect changes to limit the length of time zone abbreviations
+  and the characters used in those abbreviations.
+
+  There are also changes to handle POSIX-style "quoted" timezone
+  environment variables.
+
+  The changes were circulated on the time zone mailing list; the only
+  change since then was the removal of a couple of minimum-length of
+  abbreviation checks.
+
+
+Release data2005i - 2005-04-21 15:04:16 -0400
+
+  changes (most importantly to Nicaragua and Haiti) by Paul Eggert
+
+
+Release 2005h - 2005-04-04 11:24:47 -0400
+
+  changes by Paul Eggert
+
+  minor changes to Makefile and zdump.c to produce more useful output
+  when doing a "make typecheck"
+
+
+Release 2005g - 2005-03-14 10:11:21 -0500
+
+  changes by Paul Eggert (a change to current DST rules in Uruguay and
+  an update to a link to time zone software)
+
+
+Release 2005f - 2005-03-01 08:45:32 -0500
+
+  data and documentation changes by Paul Eggert
+
+
+Release 2005e - 2005-02-10 15:59:44 -0500
+
+  [not summarized]
+
+
+Release code2005d - 2005-01-31 09:21:47 -0500
+
+  make zic complain about links to links if the -v flag is used
+
+  have "make public" do more code checking
+
+  add an include to "localtime.c" for the benefit of gcc systems
+
+
+Release 2005c - 2005-01-17 18:36:29 -0500
+
+  get better results when mktime runs on a system where time_t is double
+
+  changes to the data files (most importantly to Paraguay)
+
+
+Release 2005b - 2005-01-10 09:19:54 -0500
+
+  Get localtime and gmtime working on systems with exotic time_t types.
+
+  Update the leap second commentary in the "leapseconds" file.
+
+
+Release 2005a - 2005-01-01 13:13:44 -0500
+
+  [not summarized]
+
+
+Release code2004i - 2004-12-14 13:42:58 -0500
+
+  Deal with systems where time_t is unsigned.
+
+
+Release code2004h - 2004-12-07 11:40:18 -0500
+
+  64-bit-time_t changes
+
+
+Release 2004g - 2004-11-02 09:06:01 -0500
+
+  update to Cuba (taking effect this weekend)
+
+  other changes by Paul Eggert
+
+  correction of the spelling of Oslo
+
+  changed versions of difftime.c and private.h
+
+
+Release code2004f - 2004-10-21 10:25:22 -0400
+
+  Cope with wide-ranging tm_year values.
+
+
+Release 2004e - 2004-10-11 14:47:21 -0400
+
+  Brazil/Argentina/Israel changes by Paul Eggert
+
+  changes to tz-link.htm by Paul
+
+  one small fix to Makefile
+
+
+Release 2004d - 2004-09-22 08:27:29 -0400
+
+  Avoid overflow problems when TM_YEAR_BASE is added to an integer.
+
+
+Release 2004c - 2004-08-11 12:06:26 -0400
+
+  asctime-related changes
+
+  (variants of) some of the documentation changes suggested by Paul Eggert
+
+
+Release 2004b - 2004-07-19 14:33:35 -0400
+
+  data changes by Paul Eggert - most importantly, updates for Argentina
+
+
+Release 2004a - 2004-05-27 12:00:47 -0400
+
+  changes by Paul Eggert
+
+  Handle DST transitions that occur at the end of a month in some
+  years but at the start of the following month in other years.
+
+  Add a copy of the correspondence that's the basis for claims about
+  DST in the Navajo Nation.
+
+
+Release 2003e - 2003-12-15 09:36:47 -0500
+
+  changes by Arthur David Olson (primarily code changes)
+
+  changes by Paul Eggert (primarily data changes)
+
+  minor changes to "Makefile" and "northamerica" (in the latter case,
+  optimization of the "Toronto" rules)
+
+
+Release 2003d - 2003-10-06 09:34:44 -0400
+
+  changes by Paul Eggert
+
+
+Release 2003c - 2003-09-16 10:47:05 -0400
+
+  Fix bad returns in zic.c's inleap function.
+  Thanks to Bradley White for catching the problem!
+
+
+Release 2003b - 2003-09-16 07:13:44 -0400
+
+  Add a "--version" option (and documentation) to the zic and zdump commands.
+
+  changes to overflow/underflow checking in zic
+
+  a localtime typo fix.
+
+  Update the leapseconds and tz-art.htm files.
+
+
+Release 2003a - 2003-03-24 09:30:54 -0500
+
+  changes by Paul Eggert
+
+  a few additions and modifications to the tz-art.htm file
+
+
+Release 2002d - 2002-10-15 13:12:42 -0400
+
+  changes by Paul Eggert, less the "Britain (UK)" change in iso3166.tab
+
+  There's also a new time zone quote in "tz-art.htm".
+
+
+Release 2002c - 2002-04-04 11:55:20 -0500
+
+  changes by Paul Eggert
+
+  Change zic.c to avoid creating symlinks to files that don't exist.
+
+
+Release 2002b - 2002-01-28 12:56:03 -0500
+
+  [These change notes are for Release 2002a, which was corrupted.
+  2002b was a corrected version of 2002a.]
+
+  changes by Paul Eggert
+
+  Update the "leapseconds" file to note that there'll be no leap
+  second at the end of June, 2002.
+
+  Change "zic.c" to deal with a problem in handling the "Asia/Bishkek" zone.
+
+  Change to "difftime.c" to avoid sizeof problems.
+
+
+Release 2001d - 2001-10-09 13:31:32 -0400
+
+  changes by Paul Eggert
+
+
+Release 2001c - 2001-06-05 13:59:55 -0400
+
+  changes by Paul Eggert and Andrew Brown
+
+
+Release 2001b - 2001-04-05 16:44:38 -0400
+
+  changes by Paul Eggert (modulo jnorgard's typo fix)
+
+  tz-art.htm has been HTMLified.
+
+
+Release 2001a - 2001-03-13 12:57:44 -0500
+
+  changes by Paul Eggert
+
+  An addition to the "leapseconds" file: comments with the text of the
+  latest IERS leap second notice.
+
+  Trailing white space has been removed from data file lines, and
+  repeated spaces in "Rule Jordan" lines in the "asia" file have been
+  converted to tabs.
+
+
+Release 2000h - 2000-12-14 15:33:38 -0500
+
+  changes by Paul Eggert
+
+  one typo fix in the "art" file
+
+  With providence, this is the last update of the millennium.
+
+
+Release 2000g - 2000-10-10 11:35:22 -0400
+
+  changes by Paul Eggert
+
+  correction of John Mackin's name submitted by Robert Elz
+
+  Garry Shandling's Daylight Saving Time joke (!?!) from the recent
+  Emmy Awards broadcast.
+
+
+Release 2000f - 2000-08-10 09:31:58 -0400
+
+  changes by Paul Eggert
+
+  Added information in "tz-art.htm" on a Seinfeld reference to DST.
+
+  Error checking and messages in the "yearistype" script have been
+  improved.
+
+
+Release 2000e - 2000-07-31 09:27:54 -0400
+
+  data changes by Paul Eggert
+
+  a change to the default value of the defined constant HAVE_STRERROR
+
+  the addition of a Dave Barry quote on DST to the tz-arts file
+
+
+Release 2000d - 2000-04-20 15:43:04 -0400
+
+  changes to the documentation and code of strftime for C99 conformance
+
+  a bug fix for date.c
+
+  These are based on (though modified from) changes by Paul Eggert.
+
+
+Release 2000c - 2000-03-04 10:31:43 -0500
+
+  changes by Paul Eggert
+
+
+Release 2000b - 2000-02-21 12:16:29 -0500
+
+  changes by Paul Eggert and Joseph Myers
+
+  modest tweaks to the tz-art.htm and tz-link.htm files
+
+
+Release 2000a - 2000-01-18 09:21:26 -0500
+
+  changes by Paul Eggert
+
+  The two hypertext documents have also been renamed.
+
+
+Release code1999i-data1999j - 1999-11-15 18:43:22 -0500
+
+  Paul Eggert's changes
+
+  additions to the "zic" manual page and the "Arts.htm" file
+
+
+Release code1999h-data1999i - 1999-11-08 14:55:21 -0500
+
+  [not summarized]
+
+
+Release data1999h - 1999-10-07 03:50:29 -0400
+
+  changes by Paul Eggert to "europe" (most importantly, fixing
+  Lithuania and Estonia)
+
+
+Release 1999g - 1999-09-28 11:06:18 -0400
+
+  data changes by Paul Eggert (most importantly, the change for
+  Lebanon that buys correctness for this coming Sunday)
+
+  The "code" file contains changes to "Makefile" and "checktab.awk" to
+  allow better checking of time zone files before they are published.
+
+
+Release 1999f - 1999-09-23 09:48:14 -0400
+
+  changes by Arthur David Olson and Paul Eggert
+
+
+Release 1999e - 1999-08-17 15:20:54 -0400
+
+  changes circulated by Paul Eggert, although the change to handling
+  of DST-specifying timezone names has been commented out for now
+  (search for "XXX" in "localtime.c" for details).  These files also
+  do not make any changes to the start of DST in Brazil.
+
+  In addition to Paul's changes, there are updates to "Arts.htm" and
+  cleanups of URLs.
+
+
+Release 1999d - 1999-03-30 11:31:07 -0500
+
+  changes by Paul Eggert
+
+  The Makefile's "make public" rule has also been changed to do a test
+  compile of each individual time zone data file (which should help
+  avoid problems such as the one we had with Nicosia).
+
+
+Release 1999c - 1999-03-25 09:47:47 -0500
+
+  changes by Paul Eggert, most importantly the change for Chile.
+
+
+Release 1999b - 1999-02-01 17:51:44 -0500
+
+  changes by Paul Eggert
+
+  code changes (suggested by Mani Varadarajan, mani at be.com) for
+  correct handling of symbolic links when building using a relative directory
+
+  code changes to generate correct messages for failed links
+
+  updates to the URLs in Arts.htm
+
+
+Release 1999a - 1999-01-19 16:20:29 -0500
+
+  error message internationalizations and corrections in zic.c and
+  zdump.c (as suggested by Vladimir Michl, vladimir.michl at upol.cz,
+  to whom thanks!)
+
+
+Release code1998h-data1998i - 1998-10-01 09:56:10 -0400
+
+  changes for Brazil, Chile, and Germany
+
+  support for use of "24:00" in the input files for the time zone compiler
+
+
+Release code1998g-data1998h - 1998-09-24 10:50:28 -0400
+
+  changes by Paul Eggert
+
+  correction to a define in the "private.h" file
+
+
+Release data1998g - 1998-08-11 03:28:35 -0000
+  [tzdata1998g.tar.gz is missing!]
+
+  Lithuanian change provided by mgedmin at pub.osf.it
+
+  Move creation of the GMT link with Etc/GMT to "etcetera" (from
+  "backward") to ensure that the GMT file is created even where folks
+  don't want the "backward" links (as suggested by Paul Eggert).
+
+
+Release data1998f - 1998-07-20 13:50:00 -0000
+  [tzdata1998f.tar.gz is missing!]
+
+  Update the "leapseconds" file to include the newly-announced
+  insertion at the end of 1998.
+
+
+Release code1998f - 1998-06-01 10:18:31 -0400
+
+  addition to localtime.c by Guy Harris
+
+
+Release 1998e - 1998-05-28 09:56:26 -0400
+
+  The Makefile is changed to produce zoneinfo-posix rather than
+  zoneinfo/posix, and to produce zoneinfo-leaps rather than
+  zoneinfo/right.
+
+  data changes by Paul Eggert
+
+  changes from Guy Harris to provide asctime_r and ctime_r
+
+  A usno1998 file (substantially identical to usno1997) has been added.
+
+
+Release 1998d - 1998-05-14 11:58:34 -0400
+
+  changes to comments (in particular, elimination of references to CIA maps).
+  "Arts.htm", "WWW.htm", "asia", and "australasia" are the only places
+  where changes occur.
+
+
+Release 1998c - 1998-02-28 12:32:26 -0500
+
+  changes by Paul Eggert (save the "French correction," on which I'll
+  wait for the dust to settle)
+
+  symlink changes
+
+  changes and additions to Arts.htm
+
+
+Release 1998b - 1998-01-17 14:31:51 -0500
+
+  URL cleanups and additions
+
+
+Release 1998a - 1998-01-13 12:37:35 -0500
+
+  changes by Paul Eggert
+
+
+Release code1997i-data1997k - 1997-12-29 09:53:41 -0500
+
+  changes by Paul Eggert, with minor modifications from Arthur David
+  Olson to make the files more browser friendly
+
+
+Release code1997h-data1997j - 1997-12-18 17:47:35 -0500
+
+  minor changes to put "TZif" at the start of each timezone information file
+
+  a rule has also been added to the Makefile so you can
+	make zones
+  to just recompile the zone information files (rather than doing a
+  full "make install" with its other effects).
+
+
+Release data1997i - 1997-10-07 08:45:38 -0400
+
+  changes to Africa by Paul Eggert
+
+
+Release code1997g-data1997h - 1997-09-04 16:56:54 -0400
+
+  corrections for Uruguay (and other locations)
+
+  Arthur David Olson's simple-minded fix allowing mktime to both
+  correctly handle leap seconds and correctly handle tm_sec values
+  upon which arithmetic has been performed.
+
+
+Release code1997f-data1997g - 1997-07-19 13:15:02 -0400
+
+  Paul Eggert's updates
+
+  a small change to a function prototype;
+
+  "Music" has been renamed "Arts.htm", HTMLified, and augmented to
+  include information on Around the World in Eighty Days.
+
+
+Release code1997e-data1997f - 1997-05-03 18:52:34 -0400
+
+  fixes to zic's error handling
+
+  changes inspired by the item circulated on Slovenia
+
+  The description of Web resources has been HTMLified for browsing
+  convenience.
+
+  A new piece of tz-related music has been added to the "Music" file.
+
+
+Release code1997d-data1997e - 1997-03-29 12:48:52 -0500
+
+  Paul Eggert's latest suggestions
+
+
+Release code1997c-data1997d - 1997-03-07 20:37:54 -0500
+
+  changes to "zic.c" to correct performance of the "-s" option
+
+  a new file "usno1997"
+
+
+Release data1997c - 1997-03-04 09:58:18 -0500
+
+  changes in Israel
+
+
+Release 1997b - 1997-02-27 18:34:19 -0500
+
+  The data file incorporates the 1997 leap second.
+
+  The code file incorporates Arthur David Olson's take on the
+  zic/multiprocessor/directory-creation situation.
+
+
+Release 1997a - 1997-01-21 09:11:10 -0500
+
+  Paul Eggert's Antarctica (and other changes)
+
+  Arthur David Olson finessed the "getopt" issue by checking against
+  both -1 and EOF (regardless of POSIX, SunOS 4.1.1's manual says -1
+  is returned while SunOS 5.5's manual says EOF is returned).
+
+
+Release code1996o-data1996n - 1996-12-27 21:42:05 -0500
+
+  Paul Eggert's latest changes
+
+
+Release code1996n - 1996-12-16 09:42:02 -0500
+
+  link snapping fix from Bruce Evans (via Garrett Wollman)
+
+
+Release data1996m - 1996-11-24 02:37:34 -0000
+  [tzdata1996m.tar.gz is missing!]
+
+  Paul Eggert's batch of changes
+
+
+Release code1996m-data1996l - 1996-11-05 14:00:12 -0500
+
+  No functional changes here; the files have simply been changed to
+  make more use of ISO style dates in comments. The names of the above
+  files now include the year in full.
+
+
+Release code96l - 1996-09-08 17:12:20 -0400
+
+  tzcode96k was missing a couple of pieces.
+
+
+Release 96k - 1996-09-08 16:06:22 -0400
+
+  the latest round of changes from Paul Eggert
+
+  the recent Year 2000 material
+
+
+Release code96j - 1996-07-30 13:18:53 -0400
+
+  Set sp->typecnt as suggested by Timothy Patrick Murphy.
+
+
+Release code96i - 1996-07-27 20:11:35 -0400
+
+  Paul's suggested patch for strftime %V week numbers
+
+
+Release data96i - 1996-07-01 18:13:04 -0400
+
+  "northamerica" and "europe" changes by Paul Eggert
+
+
+Release code96h - 1996-06-05 08:02:21 -0400
+
+  fix for handling transitions specified in Universal Time
+
+  Some "public domain" notices have also been added.
+
+
+Release code96g - 1996-05-16 14:00:26 -0400
+
+  fix for the simultaneous-DST-and-zone-change challenge
+
+
+Release data96h - 1996-05-09 17:40:51 -0400
+
+  changes by Paul Eggert
+
+
+Release code96f-data96g - 1996-05-03 03:09:59 -0000
+  [tzcode96f.tar.gz + tzdata96g.tar.gz are both missing!]
+
+  The changes get us some of the way to fixing the problems noted in Paul
+  Eggert's letter yesterday (in addition to a few others).  The approach
+  has been to make zic a bit smarter about figuring out what time zone
+  abbreviations apply just after the time specified in the "UNTIL" part
+  of a zone line.  Putting the smarts in zic means avoiding having
+  transition times show up in both "Zone" lines and "Rule" lines, which
+  in turn avoids multiple transition time entries in time zone files.
+  (This also makes the zic input files such as "europe" a bit shorter and
+  should ease maintenance.)
+
+
+Release data96f - 1996-04-19 19:20:03 -0000
+  [tzdata96f.tar.gz is missing!]
+
+  The only changes are to the "northamerica" file; the time zone
+  abbreviation for Denver is corrected to MST (and MDT), and the
+  comments for Mexico have been updated.
+
+
+Release data96e - 1996-03-19 17:37:26 -0500
+
+  Proposals by Paul Eggert, in particular the Portugal change that
+  comes into play at the end of this month.
+
+
+Release data96d - 1996-03-18 20:49:39 -0500
+
+  [not summarized]
+
+
+Release code96e - 1996-02-29 15:43:27 -0000
+  [tzcode96e.tar.gz is missing!]
+
+  internationalization changes and the fix to the documentation for strftime
+
+
+Release code96d-data96c - 1996-02-12 11:05:27 -0500
+
+  The "code" file simply updates Bob Kridle's electronic address.
+
+  The "data" file updates rules for Mexico.
+
+
+Release data96b - 1996-01-27 15:44:42 -0500
+
+  Kiribati change
+
+
+Release code96c - 1996-01-16 16:58:15 -0500
+
+  leap-year streamlining and binary-search changes
+
+  fix to newctime.3
+
+
+Release code96b - 1996-01-10 20:42:39 -0500
+
+  fixes and enhancements from Paul Eggert, including code that
+  emulates the behavior of recent versions of the SunOS "date"
+  command.
+
+
+Release 96a - 1996-01-06 09:08:24 -0500
+
+  Israel updates
+
+  fixes to strftime.c for correct ISO 8601 week number generation,
+  plus support for two new formats ('G' and 'g') to give ISO 8601 year
+  numbers (which are not necessarily the same as calendar year numbers)
+
+
+Release code95i-data95m - 1995-12-21 12:46:47 -0500
+
+  The latest revisions from Paul Eggert are included, the usno1995
+  file has been updated, and a new file ("WWW") covering useful URLs
+  has been added.
+
+
+Release code95h-data95l - 1995-12-19 18:10:12 -0500
+
+  A simplification of a macro definition, a change to data for Sudan,
+  and (for last minute shoppers) notes in the "Music" file on the CD
+  "Old Man Time".
+
+
+Release code95g-data95k - 1995-10-30 10:32:47 -0500
+
+  (slightly reformatted) 8-bit-clean proposed patch
+
+  minor patch: US/Eastern -> America/New_York
+
+  snapshot of the USNO's latest data ("usno1995")
+
+  some other minor cleanups
+
+
+Release code95f-data95j - 1995-10-28 21:01:34 -0000
+  [tzcode95f.tar.gz + tzdata95j.tar.gz are both missing!]
+
+  European cleanups
+
+  support for 64-bit time_t's
+
+  optimization in localtime.c
+
+
+Release code95e - 1995-10-13 13:23:57 -0400
+
+  the mktime change to scan from future to past when trying to find time zone
+  offsets
+
+
+Release data95i - 1995-09-26 10:43:26 -0400
+
+  For Canada/Central, guess that the Sun customer's "one week too
+  early" was just a approximation, and the true error is one month
+  too early.  This is consistent with the rest of Canada.
+
+
+Release data95h - 1995-09-21 11:26:48 -0400
+
+  latest changes from Paul Eggert
+
+
+Release code95d - 1995-09-14 11:14:45 -0400
+
+  the addition of a "Music" file, which documents four recorded
+  versions of the tune "Save That Time".
+
+
+Release data95g - 1995-09-01 17:21:36 -0400
+
+  "yearistype" correction
+
+
+Release data95f - 1995-08-28 20:46:56 -0400
+
+  Paul Eggert's change to the australasia file
+
+
+Release data95e - 1995-07-08 18:02:34 -0400
+
+  The only change is a leap second at the end of this year.
+  Thanks to Bradley White for forwarding news on the leap second.
+
+
+Release data95d - 1995-07-03 13:26:22 -0400
+
+  Paul Eggert's changes
+
+
+Release data95c - 1995-07-02 19:19:28 -0400
+
+  changes to "asia", "backward", "europe", and "southamerica"
+  (read: northamericacentrics need not apply)
+
+
+Release code95c - 1995-03-13 14:00:46 -0500
+
+  one-line fix for sign extension problems in detzcode
+
+
+Release 95b - 1995-03-04 11:22:38 -0500
+
+  Minor changes in both:
+
+  The "code" file contains a workaround for the lack of "unistd.h" in
+  Microsoft C++ version 7.
+
+  The "data" file contains a fixed "Link" for America/Shiprock.
+
+
+Release 94h - 1994-12-10 12:51:14 -0500
+
+  The files:
+
+  *	incorporate the changes to "zdump" and "date" to make changes to
+	the "TZ" environment variable permanent;
+
+  *	incorporate the table changes by Paul Eggert;
+
+  *	include (and document) support for universal time specifications in
+	data files - but do not (yet) include use of this feature in the
+	data files.
+
+  Think of this as "TZ Classic" - the software has been set up not to break if
+  universal time shows up in its input, and data entries have been
+  left as is so as not to break existing implementations.
+
+
+Release data94f - 1994-08-20 12:56:09 -0400
+
+  (with thanks!) the latest data updates from Paul Eggert
+
+
+Release data94e - 1994-06-04 13:13:53 -0400
+
+  [not summarized]
+
+
+Release code94g - 1994-05-05 12:14:07 -0400
+
+  fix missing "optind.c" and a reference to it in the Makefile
+
+
+Release code94f - 1994-05-05 13:00:33 -0000
+  [tzcode94f.tar.gz is missing!]
+
+  changes to avoid overflow in difftime, as well as changes to cope
+  with the 52/53 challenge in strftime
+
+
+Release code94e - 1994-03-30 23:32:59 -0500
+
+  change for the benefit of PCTS
+
+
+Release 94d - 1994-02-24 15:42:25 -0500
+
+  Avoid clashes with POSIX semantics for zones such as GMT+4.
+
+  Some other very minor housekeeping is also present.
+
+
+Release code94c - 1994-02-10 08:52:40 -0500
+
+  Fix bug where mkdirs was broken unless you compile with
+  -fwritable-strings (which is generally losing to do).
+
+
+Release 94b - 1994-02-07 10:04:33 -0500
+
+  work by Paul Eggert who notes:
+
+  I found another book of time zone histories by E W Whitman; it's not
+  as extensive as Shanks but has a few goodies of its own.  I used it
+  to update the tables.  I also fixed some more as a result of
+  correspondence with Adam David and Peter Ilieve, and move some stray
+  links from 'europe' to 'backward'.  I corrected some scanning errors
+  in usno1989.
+
+  As far as the code goes, I fixed zic to allow years in the range
+  INT_MIN to INT_MAX; this fixed a few boundary conditions around 1900.
+  And I cleaned up the zic documentation a little bit.
+
+
+Release data94a - 1994-02-03 08:58:54 -0500
+
+  It simply incorporates the recently announced leap second into the
+  "leapseconds" file.
+
+
+Release 93g - 1993-11-22 17:28:27 -0500
+
+  Paul Eggert has provided a good deal of historic information (based
+  on Shanks), and there are some code changes to deal with the buglets
+  that crawled out in dealing with the new information.
+
+
+Release 93f - 1993-10-15 12:27:46 -0400
+
+  Paul Eggert's changes
+
+
+Release 93e - 1993-09-05 21:21:44 -0400
+
+  This has updated data for Israel, England, and Kwajalein.  There's
+  also an update to "zdump" to cope with Kwajalein's 24-hour jump.
+  Thanks to Paul Eggert and Peter Ilieve for the changes.
+
+
+Release 93d - 1993-06-17 23:34:17 -0400
+
+  new fix and new data on Israel
+
+
+Release 93c - 1993-06-06 19:31:55 -0400
+
+  [not summarized]
+
+
+Release 93b - 1993-02-02 14:53:58 -0500
+
+  updated "leapseconds" file
+
+
+Release 93 - 1993-01-08 07:01:06 -0500
+
+  At kre's suggestion, the package has been split in two - a code piece
+  (which also includes documentation) that's only of use to folks who
+  want to recompile things and a data piece useful to anyone who can
+  run "zic".
+
+  The new version has a few changes to the data files, a few
+  portability changes, and an off-by-one fix (with thanks to
+  Tom Karzes at deshaw.com for providing a description and a
+  solution).
+
+
+Release 92c - 1992-11-21 17:35:36 -0000
+  [tz92c.tar.Z is missing!]
+
+  The fallout from the latest round of DST transitions.
+
+  There are changes for Portugal, Saskatchewan, and "Pacific-New";
+  there's also a change to "zic.c" that makes it portable to more systems.
+
+
+Release 92 - 1992-04-25 18:17:03 -0000
+  [tz92.tar.Z is missing!]
+
+  By popular demand (well, at any rate, following a request by kre at munnari)
+
+
+The 1989 update of the time zone package featured:
+
+  *	POSIXization (including interpretation of POSIX-style TZ environment
+	variables, provided by Guy Harris),
+  *	ANSIfication (including versions of "mktime" and "difftime"),
+  *	SVIDulation (an "altzone" variable)
+  *	MACHination (the "gtime" function)
+  *	corrections to some time zone data (including corrections to the rules
+	for Great Britain and New Zealand)
+  *	reference data from the United States Naval Observatory for folks who
+	want to do additional time zones
+  *	and the 1989 data for Saudi Arabia.
+
+  (Since this code will be treated as "part of the implementation" in some
+  places and as "part of the application" in others, there's no good way to
+  name functions, such as timegm, that are not part of the proposed ANSI C
+  standard; such functions have kept their old, underscore-free names in this
+  update.)
+
+  And the "dysize" function has disappeared; it was present to allow
+  compilation of the "date" command on old BSD systems, and a version of "date"
+  is now provided in the package.  The "date" command is not created when you
+  "make all" since it may lack options provided by the version distributed with
+  your operating system, or may not interact with the system in the same way
+  the native version does.
+
+  Since POSIX frowns on correct leap second handling, the default behavior of
+  the "zic" command (in the absence of a "-L" option) has been changed to omit
+  leap second information from its output files.
+
+
+-----
+Notes
+
+This file contains copies of the part of each release announcement
+that talks about the changes in that release.  The text has been
+adapted and reformatted for the purposes of this file.
+
+Traditionally a release R consists of a pair of tarball files,
+tzcodeR.tar.gz and tzdataR.tar.gz.  However, some releases (e.g.,
+code2010a, data2012c) consist of just one or the other tarball, and a
+few (e.g., code2012c-data2012d) have tarballs with mixed version
+numbers.  Recent releases also come in an experimental format
+consisting of a single tarball tzdb-R.tar.lz with extra data.
+
+Release timestamps are taken from the release's commit (for newer,
+Git-based releases), from the newest file in the tarball (for older
+releases, where this info is available) or from the email announcing
+the release (if all else fails; these are marked with a time zone
+abbreviation of -0000 and an "is missing!" comment).
+
+Earlier versions of the code and data were not announced on the tz
+list and are not summarized here.
+
+This file is in the public domain.
+
+Local Variables:
+coding: utf-8
+End:
diff --git a/contrib/tzcode/README b/contrib/tzcode/README
new file mode 100644
index 000000000000..145aacd495b7
--- /dev/null
+++ b/contrib/tzcode/README
@@ -0,0 +1,52 @@
+README for the tz distribution
+
+"Where do I set the hands of the clock?" -- Les Tremayne as The King
+"Oh that--you can set them any place you want." -- Frank Baxter as The Scientist
+					(from the Bell System film "About Time")
+
+The Time Zone Database (called tz, tzdb or zoneinfo) contains code and
+data that represent the history of local time for many representative
+locations around the globe.  It is updated periodically to reflect
+changes made by political bodies to time zone boundaries, UTC offsets,
+and daylight-saving rules.
+
+See <https://www.iana.org/time-zones/repository/tz-link.html> or the
+file tz-link.html for how to acquire the code and data.  Once acquired,
+read the comments in the file 'Makefile' and make any changes needed
+to make things right for your system, especially if you are using some
+platform other than GNU/Linux.  Then run the following commands,
+substituting your desired installation directory for "$HOME/tzdir":
+
+	make TOPDIR=$HOME/tzdir install
+	$HOME/tzdir/usr/bin/zdump -v America/Los_Angeles
+
+See the file tz-how-to.html for examples of how to read the data files.
+
+This database of historical local time information has several goals:
+
+ * Provide a compendium of data about the history of civil time that
+   is useful even if not 100% accurate.
+
+ * Give an idea of the variety of local time rules that have existed
+   in the past and thus may be expected in the future.
+
+ * Test the generality of the local time rule description system.
+
+The information in the time zone data files is by no means authoritative;
+fixes and enhancements are welcome.  Please see the file CONTRIBUTING
+for details.
+
+Thanks to these Time Zone Caballeros who've made major contributions to the
+time conversion package: Keith Bostic; Bob Devine; Paul Eggert; Robert Elz;
+Guy Harris; Mark Horton; John Mackin; and Bradley White.  Thanks also to
+Michael Bloom, Art Neilson, Stephen Prince, John Sovereign, and Frank Wales
+for testing work, and to Gwillim Law for checking local mean time data.
+Thanks in particular to Arthur David Olson, the project's founder and first
+maintainer, to whom the time zone community owes the greatest debt of all.
+None of them are responsible for remaining errors.
+
+-----
+
+This file is in the public domain, so clarified as of 2009-05-17 by
+Arthur David Olson.  The other files in this distribution are either
+public domain or BSD licensed; see the file LICENSE for details.
diff --git a/contrib/tzcode/SECURITY b/contrib/tzcode/SECURITY
new file mode 100644
index 000000000000..40128bc86dd2
--- /dev/null
+++ b/contrib/tzcode/SECURITY
@@ -0,0 +1,15 @@
+Please report any sensitive security-related bugs via email to the
+tzdb designated coordinators, currently Paul Eggert
+<eggert@cs.ucla.edu> and Tim Parenti <tim@timtimeonline.com>.
+Put "tzdb security" at the start of your email's subject line.
+We prefer communications to be in English.
+
+You should receive a response within a week. If not, please follow up
+via email to make sure we received your original message.
+
+If we confirm the bug, we plan to notify affected third-party services
+or software that we know about, prepare an advisory, commit fixes to
+the main development branch as quickly as is practical, and finally
+publish the advisory on tz@iana.org.  As with all tzdb contributions,
+we give credit to security contributors unless they wish to remain
+anonymous.
diff --git a/contrib/tzcode/stdtime/asctime.c b/contrib/tzcode/asctime.c
index be865fb807c1..1a6486f38163 100644
--- a/contrib/tzcode/stdtime/asctime.c
+++ b/contrib/tzcode/asctime.c
@@ -1,3 +1,5 @@
+/* asctime and asctime_r a la POSIX and ISO C, except pad years before 1000.  */
+
 /*
 ** This file is in the public domain, so clarified as of
 ** 1996-06-05 by Arthur David Olson.
@@ -9,28 +11,14 @@
 ** whereas the output of asctime is supposed to be constant.
 */
 
-#include <sys/cdefs.h>
-#ifndef lint
-#ifndef NOID
-static char	elsieid[] __unused = "@(#)asctime.c	8.5";
-#endif /* !defined NOID */
-#endif /* !defined lint */
-__FBSDID("$FreeBSD$");
-
 /*LINTLIBRARY*/
 
 #include "namespace.h"
 #include "private.h"
 #include "un-namespace.h"
-#include "tzfile.h"
+#include <stdio.h>
 
 /*
-** Some systems only handle "%.2d"; others only handle "%02d";
-** "%02.2d" makes (most) everybody happy.
-** At least some versions of gcc warn about the %02.2d;
-** we conditionalize below to avoid the warning.
-*/
-/*
 ** All years associated with 32-bit time_t values are exactly four digits long;
 ** some years associated with 64-bit time_t values are not.
 ** Vintage programs are coded for years that are always four digits long
@@ -39,61 +27,45 @@ __FBSDID("$FreeBSD$");
 ** leading zeroes to get the newline in the traditional place.
 ** The -4 ensures that we get four characters of output even if
 ** we call a strftime variant that produces fewer characters for some years.
-** The ISO C 1999 and POSIX 1003.1-2004 standards prohibit padding the year,
+** The ISO C and POSIX standards prohibit padding the year,
 ** but many implementations pad anyway; most likely the standards are buggy.
 */
-#ifdef __GNUC__
-#define ASCTIME_FMT	"%.3s %.3s%3d %2.2d:%2.2d:%2.2d %-4s\n"
-#else /* !defined __GNUC__ */
-#define ASCTIME_FMT	"%.3s %.3s%3d %02.2d:%02.2d:%02.2d %-4s\n"
-#endif /* !defined __GNUC__ */
+static char const ASCTIME_FMT[] = "%s %s%3d %.2d:%.2d:%.2d %-4s\n";
 /*
 ** For years that are more than four digits we put extra spaces before the year
 ** so that code trying to overwrite the newline won't end up overwriting
 ** a digit within a year and truncating the year (operating on the assumption
 ** that no output is better than wrong output).
 */
-#ifdef __GNUC__
-#define ASCTIME_FMT_B	"%.3s %.3s%3d %2.2d:%2.2d:%2.2d     %s\n"
-#else /* !defined __GNUC__ */
-#define ASCTIME_FMT_B	"%.3s %.3s%3d %02.2d:%02.2d:%02.2d     %s\n"
-#endif /* !defined __GNUC__ */
+static char const ASCTIME_FMT_B[] = "%s %s%3d %.2d:%.2d:%.2d     %s\n";
 
-#define STD_ASCTIME_BUF_SIZE	26
+enum { STD_ASCTIME_BUF_SIZE = 26 };
 /*
 ** Big enough for something such as
 ** ??? ???-2147483648 -2147483648:-2147483648:-2147483648     -2147483648\n
 ** (two three-character abbreviations, five strings denoting integers,
 ** seven explicit spaces, two explicit colons, a newline,
-** and a trailing ASCII nul).
+** and a trailing NUL byte).
 ** The values above are for systems where an int is 32 bits and are provided
-** as an example; the define below calculates the maximum for the system at
+** as an example; the size expression below is a bound for the system at
 ** hand.
 */
-#define MAX_ASCTIME_BUF_SIZE	(2*3+5*INT_STRLEN_MAXIMUM(int)+7+2+1+1)
-
-static char	buf_asctime[MAX_ASCTIME_BUF_SIZE];
-
-/*
-** A la ISO/IEC 9945-1, ANSI/IEEE Std 1003.1, 2004 Edition.
-*/
+static char buf_asctime[2*3 + 5*INT_STRLEN_MAXIMUM(int) + 7 + 2 + 1 + 1];
 
 char *
-asctime_r(timeptr, buf)
-const struct tm *	timeptr;
-char *			buf;
+asctime_r(register const struct tm *timeptr, char *buf)
 {
-	static const char	wday_name[][3] = {
+	static const char	wday_name[][4] = {
 		"Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"
 	};
-	static const char	mon_name[][3] = {
+	static const char	mon_name[][4] = {
 		"Jan", "Feb", "Mar", "Apr", "May", "Jun",
 		"Jul", "Aug", "Sep", "Oct", "Nov", "Dec"
 	};
 	const char *	wn;
 	const char *	mn;
 	char			year[INT_STRLEN_MAXIMUM(int) + 2];
-	char			result[MAX_ASCTIME_BUF_SIZE];
+	char result[sizeof buf_asctime];
 
 	if (timeptr == NULL) {
 		errno = EINVAL;
@@ -111,11 +83,11 @@ char *			buf;
 	** Assume that strftime is unaffected by other out-of-range members
 	** (e.g., timeptr->tm_mday) when processing "%Y".
 	*/
-	(void) strftime(year, sizeof year, "%Y", timeptr);
+	strftime(year, sizeof year, "%Y", timeptr);
 	/*
 	** We avoid using snprintf since it's not available on all systems.
 	*/
-	(void) sprintf(result,
+	sprintf(result,
 		((strlen(year) <= 4) ? ASCTIME_FMT : ASCTIME_FMT_B),
 		wn, mn,
 		timeptr->tm_mday, timeptr->tm_hour,
@@ -124,22 +96,13 @@ char *			buf;
 	if (strlen(result) < STD_ASCTIME_BUF_SIZE || buf == buf_asctime)
 		return strcpy(buf, result);
 	else {
-#ifdef EOVERFLOW
 		errno = EOVERFLOW;
-#else /* !defined EOVERFLOW */
-		errno = EINVAL;
-#endif /* !defined EOVERFLOW */
 		return NULL;
 	}
 }
 
-/*
-** A la ISO/IEC 9945-1, ANSI/IEEE Std 1003.1, 2004 Edition.
-*/
-
 char *
-asctime(timeptr)
-const struct tm *	timeptr;
+asctime(register const struct tm *timeptr)
 {
 	return asctime_r(timeptr, buf_asctime);
 }
diff --git a/contrib/tzcode/calendars b/contrib/tzcode/calendars
new file mode 100644
index 000000000000..f4ed9e434e50
--- /dev/null
+++ b/contrib/tzcode/calendars
@@ -0,0 +1,173 @@
+----- Calendrical issues -----
+
+As mentioned in Theory.html, although calendrical issues are out of
+scope for tzdb, they indicate the sort of problems that we would run
+into if we extended tzdb further into the past.  The following
+information and sources go beyond Theory.html's brief discussion.
+They sometimes disagree.
+
+
+France
+
+Gregorian calendar adopted 1582-12-20.
+French Revolutionary calendar used 1793-11-24 through 1805-12-31,
+and (in Paris only) 1871-05-06 through 1871-05-23.
+
+
+Russia
+
+From Chris Carrier (1996-12-02):
+On 1929-10-01 the Soviet Union instituted an "Eternal Calendar"
+with 30-day months plus 5 holidays, with a 5-day week.
+On 1931-12-01 it changed to a 6-day week; in 1934 it reverted to the
+Gregorian calendar while retaining the 6-day week; on 1940-06-27 it
+reverted to the 7-day week.  With the 6-day week the usual days
+off were the 6th, 12th, 18th, 24th and 30th of the month.
+(Source: Evitiar Zerubavel, _The Seven Day Circle_)
+
+
+Mark Brader reported a similar story in "The Book of Calendars", edited
+by Frank Parise (1982, Facts on File, ISBN 0-8719-6467-8), page 377.  But:
+
+From: Petteri Sulonen (via Usenet)
+Date: 14 Jan 1999 00:00:00 GMT
+...
+
+If your source is correct, how come documents between 1929 and 1940 were
+still dated using the conventional, Gregorian calendar?
+
+I can post a scan of a document dated December 1, 1934, signed by
+Yenukidze, the secretary, on behalf of Kalinin, the President of the
+Executive Committee of the Supreme Soviet, if you like.
+
+
+
+Sweden (and Finland)
+
+From: Mark Brader
+Subject: Re: Gregorian reform - a part of locale?
+<news:1996Jul6.012937.29190@sq.com>
+Date: 1996-07-06
+
+In 1700, Denmark made the transition from Julian to Gregorian.  Sweden
+decided to *start* a transition in 1700 as well, but rather than have one of
+those unsightly calendar gaps :-), they simply decreed that the next leap
+year after 1696 would be in 1744 - putting the whole country on a calendar
+different from both Julian and Gregorian for a period of 40 years.
+
+However, in 1704 something went wrong and the plan was not carried through;
+they did, after all, have a leap year that year.  And one in 1708.  In 1712
+they gave it up and went back to Julian, putting 30 days in February that
+year!...
+
+Then in 1753, Sweden made the transition to Gregorian in the usual manner,
+getting there only 13 years behind the original schedule.
+
+(A previous posting of this story was challenged, and Swedish readers
+produced the following references to support it: "Tideräkning och historia"
+by Natanael Beckman (1924) and "Tid, en bok om tideräkning och
+kalenderväsen" by Lars-Olof Lodén (1968).
+
+
+Grotefend's data
+
+From: "Michael Palmer" [with two obvious typos fixed]
+Subject: Re: Gregorian Calendar (was Re: Another FHC related question
+Newsgroups: soc.genealogy.german
+Date: Tue, 9 Feb 1999 02:32:48 -800
+...
+
+The following is a(n incomplete) listing, arranged chronologically, of
+European states, with the date they converted from the Julian to the
+Gregorian calendar:
+
+04/15 Oct 1582 - Italy (with exceptions), Spain, Portugal, Poland (Roman
+                 Catholics and Danzig only)
+09/20 Dec 1582 - France, Lorraine
+
+21 Dec 1582/
+   01 Jan 1583 - Holland, Brabant, Flanders, Hennegau
+10/21 Feb 1583 - bishopric of Liege (Lüttich)
+13/24 Feb 1583 - bishopric of Augsburg
+04/15 Oct 1583 - electorate of Trier
+05/16 Oct 1583 - Bavaria, bishoprics of Freising, Eichstedt, Regensburg,
+                 Salzburg, Brixen
+13/24 Oct 1583 - Austrian Oberelsaß and Breisgau
+20/31 Oct 1583 - bishopric of Basel
+02/13 Nov 1583 - duchy of Jülich-Berg
+02/13 Nov 1583 - electorate and city of Köln
+04/15 Nov 1583 - bishopric of Würzburg
+11/22 Nov 1583 - electorate of Mainz
+16/27 Nov 1583 - bishopric of Strassburg and the margraviate of Baden
+17/28 Nov 1583 - bishopric of Münster and duchy of Cleve
+14/25 Dec 1583 - Steiermark
+
+06/17 Jan 1584 - Austria and Bohemia
+11/22 Jan 1584 - Lucerne, Uri, Schwyz, Zug, Freiburg, Solothurn
+12/23 Jan 1584 - Silesia and the Lausitz
+22 Jan/
+   02 Feb 1584 - Hungary (legally on 21 Oct 1587)
+      Jun 1584 - Unterwalden
+01/12 Jul 1584 - duchy of Westfalen
+
+16/27 Jun 1585 - bishopric of Paderborn
+
+14/25 Dec 1590 - Transylvania
+
+22 Aug/
+   02 Sep 1612 - duchy of Prussia
+
+13/24 Dec 1614 - Pfalz-Neuburg
+
+          1617 - duchy of Kurland (reverted to the Julian calendar in
+                 1796)
+
+          1624 - bishopric of Osnabrück
+
+          1630 - bishopric of Minden
+
+15/26 Mar 1631 - bishopric of Hildesheim
+
+          1655 - Kanton Wallis
+
+05/16 Feb 1682 - city of Strassburg
+
+18 Feb/
+   01 Mar 1700 - Protestant Germany (including Swedish possessions in
+                 Germany), Denmark, Norway
+30 Jun/
+   12 Jul 1700 - Gelderland, Zutphen
+10 Nov/
+   12 Dec 1700 - Utrecht, Overijssel
+
+31 Dec 1700/
+   12 Jan 1701 - Friesland, Groningen, Zürich, Bern, Basel, Geneva,
+                 Thurgau, and Schaffhausen
+
+          1724 - Glarus, Appenzell, and the city of St. Gallen
+
+01 Jan 1750    - Pisa and Florence
+
+02/14 Sep 1752 - Great Britain
+
+17 Feb/
+   01 Mar 1753 - Sweden
+
+1760-1812      - Graubünden
+
+The Russian empire (including Finland and the Baltic states) did not
+convert to the Gregorian calendar until the Soviet revolution of 1917.
+
+Source: H. Grotefend, _Taschenbuch der Zeitrechnung des deutschen
+Mittelalters und der Neuzeit_, herausgegeben von Dr. O. Grotefend
+(Hannover: Hahnsche Buchhandlung, 1941), pp. 26-28.
+
+-----
+
+This file is in the public domain, so clarified as of 2009-05-17 by
+Arthur David Olson.
+
+-----
+Local Variables:
+coding: utf-8
+End:
diff --git a/contrib/tzcode/date.1 b/contrib/tzcode/date.1
new file mode 100644
index 000000000000..043e568117df
--- /dev/null
+++ b/contrib/tzcode/date.1
@@ -0,0 +1,167 @@
+.\" This file is in the public domain, so clarified as of
+.\" 2009-05-17 by Arthur David Olson.
+.TH date 1
+.SH NAME
+date \- show and set date and time
+.SH SYNOPSIS
+.if n .nh
+.if n .na
+.ie \n(.g .ds - \f(CR-\fP
+.el .ds - \-
+.B date
+[
+.B \*-u
+] [
+.B \*-c
+] [
+.B \*-r
+.I seconds
+] [
+.BI + format
+] [
+\fR[\fIyyyy\fR]\fImmddhhmm\fR[\fIyy\fR][\fB.\fIss\fR]
+]
+.SH DESCRIPTION
+.ie '\(lq'' .ds lq \&"\"
+.el .ds lq \(lq\"
+.ie '\(rq'' .ds rq \&"\"
+.el .ds rq \(rq\"
+.de q
+\\$3\*(lq\\$1\*(rq\\$2
+..
+The
+.B date
+command
+without arguments writes the date and time to the standard output in
+the form
+.ce 1
+Wed Mar  8 14:54:40 EST 1989
+.br
+with
+.B EST
+replaced by the local time zone's abbreviation
+(or by the abbreviation for the time zone specified in the
+.B TZ
+environment variable if set).
+The exact output format depends on the locale.
+.PP
+If a command-line argument starts with a plus sign (\c
+.q "\fB+\fP" ),
+the rest of the argument is used as a
+.I format
+that controls what appears in the output.
+In the format, when a percent sign (\c
+.q "\fB%\fP"
+appears,
+it and the character after it are not output,
+but rather identify part of the date or time
+to be output in a particular way
+(or identify a special character to output):
+.nf
+.sp
+.if t .in +.5i
+.if n .in +2
+.ta \w'%M\0\0'u +\w'Wed Mar  8 14:54:40 EST 1989\0\0'u
+	Sample output	Explanation
+%a	Wed	Abbreviated weekday name*
+%A	Wednesday	Full weekday name*
+%b	Mar	Abbreviated month name*
+%B	March	Full month name*
+%c	Wed Mar 08 14:54:40 1989	Date and time*
+%C	19	Century
+%d	08	Day of month (always two digits)
+%D	03/08/89	Month/day/year (eight characters)
+%e	 8	Day of month (leading zero blanked)
+%h	Mar	Abbreviated month name*
+%H	14	24-hour-clock hour (two digits)
+%I	02	12-hour-clock hour (two digits)
+%j	067	Julian day number (three digits)
+%k	 2	12-hour-clock hour (leading zero blanked)
+%l	14	24-hour-clock hour (leading zero blanked)
+%m	03	Month number (two digits)
+%M	54	Minute (two digits)
+%n	\\n	newline character
+%p	PM	AM/PM designation
+%r	02:54:40 PM	Hour:minute:second AM/PM designation
+%R	14:54	Hour:minute
+%S	40	Second (two digits)
+%t	\\t	tab character
+%T	14:54:40	Hour:minute:second
+%U	10	Sunday-based week number (two digits)
+%w	3	Day number (one digit, Sunday is 0)
+%W	10	Monday-based week number (two digits)
+%x	03/08/89	Date*
+%X	14:54:40	Time*
+%y	89	Last two digits of year
+%Y	1989	Year in full
+%z	-0500	Numeric time zone
+%Z	EST	Time zone abbreviation
+%+	Wed Mar  8 14:54:40 EST 1989	Default output format*
+.if t .in -.5i
+.if n .in -2
+* The exact output depends on the locale.
+.sp
+.fi
+If a character other than one of those shown above appears after
+a percent sign in the format,
+that following character is output.
+All other characters in the format are copied unchanged to the output;
+a newline character is always added at the end of the output.
+.PP
+In Sunday-based week numbering,
+the first Sunday of the year begins week 1;
+days preceding it are part of
+.q "week 0" .
+In Monday-based week numbering,
+the first Monday of the year begins week 1.
+.PP
+To set the date, use a command line argument with one of the following forms:
+.nf
+.if t .in +.5i
+.if n .in +2
+.ta \w'198903081454\0'u
+1454	24-hour-clock hours (first two digits) and minutes
+081454	Month day (first two digits), hours, and minutes
+03081454	Month (two digits, January is 01), month day, hours, minutes
+8903081454	Year, month, month day, hours, minutes
+0308145489	Month, month day, hours, minutes, year
+	(on System V-compatible systems)
+030814541989	Month, month day, hours, minutes, four-digit year
+198903081454	Four-digit year, month, month day, hours, minutes
+.if t .in -.5i
+.if n .in -2
+.fi
+If the century, year, month, or month day is not given,
+the current value is used.
+Any of the above forms may be followed by a period and two digits that give
+the seconds part of the new time; if no seconds are given, zero is assumed.
+.PP
+These options are available:
+.TP
+.BR \*-u " or " \*-c
+Use Universal Time when setting and showing the date and time.
+.TP
+.BI "\*-r " seconds
+Output the date that corresponds to
+.I seconds
+past the epoch of 1970-01-01 00:00:00 UTC, where
+.I seconds
+should be an integer, either decimal, octal (leading 0), or
+hexadecimal (leading 0x), preceded by an optional sign.
+.SH FILES
+.ta \w'/usr/share/zoneinfo/posixrules\0\0'u
+/etc/localtime	local timezone file
+.br
+/usr/lib/locale/\f2L\fP/LC_TIME	description of time locale \f2L\fP
+.br
+/usr/share/zoneinfo	timezone information directory
+.br
+/usr/share/zoneinfo/posixrules	used with POSIX-style TZ's
+.br
+/usr/share/zoneinfo/GMT	for UTC leap seconds
+.sp
+If
+.B /usr/share/zoneinfo/GMT
+is absent,
+UTC leap seconds are loaded from
+.BR /usr/share/zoneinfo/posixrules .
diff --git a/contrib/tzcode/date.c b/contrib/tzcode/date.c
new file mode 100644
index 000000000000..11c5e5fe8d49
--- /dev/null
+++ b/contrib/tzcode/date.c
@@ -0,0 +1,216 @@
+/* Display or set the current time and date.  */
+
+/* Copyright 1985, 1987, 1988 The Regents of the University of California.
+   All rights reserved.
+
+   Redistribution and use in source and binary forms, with or without
+   modification, are permitted provided that the following conditions
+   are met:
+   1. Redistributions of source code must retain the above copyright
+      notice, this list of conditions and the following disclaimer.
+   2. Redistributions in binary form must reproduce the above copyright
+      notice, this list of conditions and the following disclaimer in the
+      documentation and/or other materials provided with the distribution.
+   3. Neither the name of the University nor the names of its contributors
+      may be used to endorse or promote products derived from this software
+      without specific prior written permission.
+
+   THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS "AS IS" AND
+   ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+   IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+   ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+   FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+   DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+   OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+   HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+   LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+   OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+   SUCH DAMAGE.  */
+
+#include "private.h"
+#include <locale.h>
+#include <stdio.h>
+
+#if !HAVE_POSIX_DECLS
+extern char *		optarg;
+extern int		optind;
+#endif
+
+static int		retval = EXIT_SUCCESS;
+
+static void		display(const char *, time_t);
+static void		dogmt(void);
+static void		errensure(void);
+static void		timeout(FILE *, const char *, const struct tm *);
+static ATTRIBUTE_NORETURN void usage(void);
+
+int
+main(const int argc, char *argv[])
+{
+	register const char *	format = "+%+";
+	register int		ch;
+	register bool		rflag = false;
+	time_t			t;
+	intmax_t		secs;
+	char *			endarg;
+
+#ifdef LC_ALL
+	setlocale(LC_ALL, "");
+#endif /* defined(LC_ALL) */
+#if HAVE_GETTEXT
+# ifdef TZ_DOMAINDIR
+	bindtextdomain(TZ_DOMAIN, TZ_DOMAINDIR);
+# endif /* defined(TEXTDOMAINDIR) */
+	textdomain(TZ_DOMAIN);
+#endif /* HAVE_GETTEXT */
+	t = time(NULL);
+	while ((ch = getopt(argc, argv, "ucr:")) != EOF && ch != -1) {
+		switch (ch) {
+		default:
+			usage();
+		case 'u':		/* do it in UT */
+		case 'c':
+			dogmt();
+			break;
+		case 'r':		/* seconds since 1970 */
+			if (rflag) {
+				fprintf(stderr,
+					_("date: error: multiple -r's used"));
+				usage();
+			}
+			rflag = true;
+			errno = 0;
+			secs = strtoimax(optarg, &endarg, 0);
+			if (*endarg || optarg == endarg)
+				errno = EINVAL;
+			else if (! (TIME_T_MIN <= secs && secs <= TIME_T_MAX))
+				errno = ERANGE;
+			if (errno) {
+				perror(optarg);
+				errensure();
+				exit(retval);
+			}
+			t = secs;
+			break;
+		}
+	}
+	if (optind < argc) {
+	  if (argc - optind != 1) {
+	    fprintf(stderr,
+		    _("date: error: multiple operands in command line\n"));
+	    usage();
+	  }
+	  format = argv[optind];
+	  if (*format != '+') {
+	    fprintf(stderr, _("date: unknown operand: %s\n"), format);
+	    usage();
+	  }
+	}
+
+	display(format, t);
+	return retval;
+}
+
+static void
+dogmt(void)
+{
+	static char **	fakeenv;
+
+	if (fakeenv == NULL) {
+		static char	tzeutc0[] = "TZ=UTC0";
+		ptrdiff_t from, to, n;
+
+		for (n = 0;  environ[n] != NULL;  ++n)
+			continue;
+#if defined ckd_add && defined ckd_mul
+		if (!ckd_add(&n, n, 2) && !ckd_mul(&n, n, sizeof *fakeenv)
+		    && n <= SIZE_MAX)
+		  fakeenv = malloc(n);
+#else
+		if (n <= min(PTRDIFF_MAX, SIZE_MAX) / sizeof *fakeenv - 2)
+		  fakeenv = malloc((n + 2) * sizeof *fakeenv);
+#endif
+		if (fakeenv == NULL) {
+			fprintf(stderr, _("date: Memory exhausted\n"));
+			errensure();
+			exit(retval);
+		}
+		to = 0;
+		fakeenv[to++] = tzeutc0;
+		for (from = 1; environ[from] != NULL; ++from)
+			if (strncmp(environ[from], "TZ=", 3) != 0)
+				fakeenv[to++] = environ[from];
+		fakeenv[to] = NULL;
+		environ = fakeenv;
+	}
+}
+
+static void
+errensure(void)
+{
+	if (retval == EXIT_SUCCESS)
+		retval = EXIT_FAILURE;
+}
+
+static void
+usage(void)
+{
+	fprintf(stderr,
+		       _("date: usage: date [-u] [-c] [-r seconds]"
+			 " [+format]\n"));
+	errensure();
+	exit(retval);
+}
+
+static void
+display(char const *format, time_t now)
+{
+	struct tm *tmp;
+
+	tmp = localtime(&now);
+	if (!tmp) {
+		fprintf(stderr,
+			_("date: error: time out of range\n"));
+		errensure();
+		return;
+	}
+	timeout(stdout, format, tmp);
+	putchar('\n');
+	fflush(stdout);
+	fflush(stderr);
+	if (ferror(stdout) || ferror(stderr)) {
+		fprintf(stderr,
+			_("date: error: couldn't write results\n"));
+		errensure();
+	}
+}
+
+static void
+timeout(FILE *fp, char const *format, struct tm const *tmp)
+{
+	char *cp = NULL;
+	ptrdiff_t result;
+	ptrdiff_t size = 1024 / 2;
+
+	for ( ; ; ) {
+#ifdef ckd_mul
+		bool bigger = !ckd_mul(&size, size, 2) && size <= SIZE_MAX;
+#else
+		bool bigger = (size <= min(PTRDIFF_MAX, SIZE_MAX) / 2
+			       && (size *= 2, true));
+#endif
+		char *newcp = bigger ? realloc(cp, size) : NULL;
+		if (!newcp) {
+			fprintf(stderr,
+				_("date: error: can't get memory\n"));
+			errensure();
+			exit(retval);
+		}
+		cp = newcp;
+		result = strftime(cp, size, format, tmp);
+		if (result != 0)
+			break;
+	}
+	fwrite(cp + 1, 1, result - 1, fp);
+	free(cp);
+}
diff --git a/contrib/tzcode/difftime.c b/contrib/tzcode/difftime.c
new file mode 100644
index 000000000000..43af402cdc12
--- /dev/null
+++ b/contrib/tzcode/difftime.c
@@ -0,0 +1,62 @@
+/* Return the difference between two timestamps.  */
+
+/*
+** This file is in the public domain, so clarified as of
+** 1996-06-05 by Arthur David Olson.
+*/
+
+/*LINTLIBRARY*/
+
+#include "namespace.h"
+#include "private.h"	/* for time_t and TYPE_SIGNED */
+#include "un-namespace.h"
+
+/* Return -X as a double.  Using this avoids casting to 'double'.  */
+static double
+dminus(double x)
+{
+  return -x;
+}
+
+double
+difftime(time_t time1, time_t time0)
+{
+	/*
+	** If double is large enough, simply convert and subtract
+	** (assuming that the larger type has more precision).
+	*/
+	if (sizeof(time_t) < sizeof(double)) {
+	  double t1 = time1, t0 = time0;
+	  return t1 - t0;
+	}
+
+	/*
+	** The difference of two unsigned values can't overflow
+	** if the minuend is greater than or equal to the subtrahend.
+	*/
+	if (!TYPE_SIGNED(time_t))
+	  return time0 <= time1 ? time1 - time0 : dminus(time0 - time1);
+
+	/* Use uintmax_t if wide enough.  */
+	if (sizeof(time_t) <= sizeof(uintmax_t)) {
+	  uintmax_t t1 = time1, t0 = time0;
+	  return time0 <= time1 ? t1 - t0 : dminus(t0 - t1);
+	}
+
+	/*
+	** Handle cases where both time1 and time0 have the same sign
+	** (meaning that their difference cannot overflow).
+	*/
+	if ((time1 < 0) == (time0 < 0))
+	  return time1 - time0;
+
+	/*
+	** The values have opposite signs and uintmax_t is too narrow.
+	** This suffers from double rounding; attempt to lessen that
+	** by using long double temporaries.
+	*/
+	{
+	  long double t1 = time1, t0 = time0;
+	  return t1 - t0;
+	}
+}
diff --git a/contrib/tzcode/localtime.c b/contrib/tzcode/localtime.c
new file mode 100644
index 000000000000..2dbab26509d3
--- /dev/null
+++ b/contrib/tzcode/localtime.c
@@ -0,0 +1,2669 @@
+/* Convert timestamp from time_t to struct tm.  */
+
+/*
+** This file is in the public domain, so clarified as of
+** 1996-06-05 by Arthur David Olson.
+*/
+
+/*
+** Leap second handling from Bradley White.
+** POSIX-style TZ environment variable handling from Guy Harris.
+*/
+
+/*LINTLIBRARY*/
+
+#define LOCALTIME_IMPLEMENTATION
+#include "namespace.h"
+#ifdef DETECT_TZ_CHANGES
+#ifndef DETECT_TZ_CHANGES_INTERVAL
+#define DETECT_TZ_CHANGES_INTERVAL 61
+#endif
+#include <sys/stat.h>
+#endif
+#include <fcntl.h>
+#if THREAD_SAFE
+#include <pthread.h>
+#endif
+#include "private.h"
+#include "un-namespace.h"
+
+#include "tzfile.h"
+
+#include "libc_private.h"
+
+#if defined THREAD_SAFE && THREAD_SAFE
+static pthread_mutex_t locallock = PTHREAD_MUTEX_INITIALIZER;
+static int lock(void) {
+	if (__isthreaded)
+		return _pthread_mutex_lock(&locallock);
+	return 0;
+}
+static void unlock(void) {
+	if (__isthreaded)
+		_pthread_mutex_unlock(&locallock);
+}
+#else
+static int lock(void) { return 0; }
+static void unlock(void) { }
+#endif
+
+#ifndef TZ_ABBR_MAX_LEN
+# define TZ_ABBR_MAX_LEN 16
+#endif /* !defined TZ_ABBR_MAX_LEN */
+
+#ifndef TZ_ABBR_CHAR_SET
+# define TZ_ABBR_CHAR_SET \
+	"abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789 :+-._"
+#endif /* !defined TZ_ABBR_CHAR_SET */
+
+#ifndef TZ_ABBR_ERR_CHAR
+# define TZ_ABBR_ERR_CHAR '_'
+#endif /* !defined TZ_ABBR_ERR_CHAR */
+
+/*
+** Support non-POSIX platforms that distinguish between text and binary files.
+*/
+
+#ifndef O_BINARY
+# define O_BINARY 0
+#endif
+
+#ifndef WILDABBR
+/*
+** Someone might make incorrect use of a time zone abbreviation:
+**	1.	They might reference tzname[0] before calling tzset (explicitly
+**		or implicitly).
+**	2.	They might reference tzname[1] before calling tzset (explicitly
+**		or implicitly).
+**	3.	They might reference tzname[1] after setting to a time zone
+**		in which Daylight Saving Time is never observed.
+**	4.	They might reference tzname[0] after setting to a time zone
+**		in which Standard Time is never observed.
+**	5.	They might reference tm.TM_ZONE after calling offtime.
+** What's best to do in the above cases is open to debate;
+** for now, we just set things up so that in any of the five cases
+** WILDABBR is used. Another possibility: initialize tzname[0] to the
+** string "tzname[0] used before set", and similarly for the other cases.
+** And another: initialize tzname[0] to "ERA", with an explanation in the
+** manual page of what this "time zone abbreviation" means (doing this so
+** that tzname[0] has the "normal" length of three characters).
+*/
+# define WILDABBR "   "
+#endif /* !defined WILDABBR */
+
+static const char	wildabbr[] = WILDABBR;
+
+static char const etc_utc[] = "Etc/UTC";
+static char const *utc = etc_utc + sizeof "Etc/" - 1;
+
+/*
+** The DST rules to use if TZ has no rules and we can't load TZDEFRULES.
+** Default to US rules as of 2017-05-07.
+** POSIX does not specify the default DST rules;
+** for historical reasons, US rules are a common default.
+*/
+#ifndef TZDEFRULESTRING
+# define TZDEFRULESTRING ",M3.2.0,M11.1.0"
+#endif
+
+struct ttinfo {				/* time type information */
+	int_fast32_t	tt_utoff;	/* UT offset in seconds */
+	bool		tt_isdst;	/* used to set tm_isdst */
+	int		tt_desigidx;	/* abbreviation list index */
+	bool		tt_ttisstd;	/* transition is std time */
+	bool		tt_ttisut;	/* transition is UT */
+};
+
+struct lsinfo {				/* leap second information */
+	time_t		ls_trans;	/* transition time */
+	int_fast32_t	ls_corr;	/* correction to apply */
+};
+
+/* This abbreviation means local time is unspecified.  */
+static char const UNSPEC[] = "-00";
+
+/* How many extra bytes are needed at the end of struct state's chars array.
+   This needs to be at least 1 for null termination in case the input
+   data isn't properly terminated, and it also needs to be big enough
+   for ttunspecified to work without crashing.  */
+enum { CHARS_EXTRA = max(sizeof UNSPEC, 2) - 1 };
+
+#ifdef TZNAME_MAX
+# define MY_TZNAME_MAX TZNAME_MAX
+#endif /* defined TZNAME_MAX */
+#ifndef TZNAME_MAX
+# define MY_TZNAME_MAX 255
+#endif /* !defined TZNAME_MAX */
+
+struct state {
+	int		leapcnt;
+	int		timecnt;
+	int		typecnt;
+	int		charcnt;
+	bool		goback;
+	bool		goahead;
+	time_t		ats[TZ_MAX_TIMES];
+	unsigned char	types[TZ_MAX_TIMES];
+	struct ttinfo	ttis[TZ_MAX_TYPES];
+	char chars[max(max(TZ_MAX_CHARS + CHARS_EXTRA, sizeof "UTC"),
+		       2 * (MY_TZNAME_MAX + 1))];
+	struct lsinfo	lsis[TZ_MAX_LEAPS];
+
+	/* The time type to use for early times or if no transitions.
+	   It is always zero for recent tzdb releases.
+	   It might be nonzero for data from tzdb 2018e or earlier.  */
+	int defaulttype;
+};
+
+enum r_type {
+  JULIAN_DAY,		/* Jn = Julian day */
+  DAY_OF_YEAR,		/* n = day of year */
+  MONTH_NTH_DAY_OF_WEEK	/* Mm.n.d = month, week, day of week */
+};
+
+struct rule {
+	enum r_type	r_type;		/* type of rule */
+	int		r_day;		/* day number of rule */
+	int		r_week;		/* week number of rule */
+	int		r_mon;		/* month number of rule */
+	int_fast32_t	r_time;		/* transition time of rule */
+};
+
+static struct tm *gmtsub(struct state const *, time_t const *, int_fast32_t,
+			 struct tm *);
+static bool increment_overflow(int *, int);
+static bool increment_overflow_time(time_t *, int_fast32_t);
+static int_fast32_t leapcorr(struct state const *, time_t);
+static bool normalize_overflow32(int_fast32_t *, int *, int);
+static struct tm *timesub(time_t const *, int_fast32_t, struct state const *,
+			  struct tm *);
+static bool typesequiv(struct state const *, int, int);
+static bool tzparse(char const *, struct state *, struct state *);
+
+#ifdef ALL_STATE
+static struct state *	lclptr;
+static struct state *	gmtptr;
+#endif /* defined ALL_STATE */
+
+#ifndef ALL_STATE
+static struct state	lclmem;
+static struct state	gmtmem;
+static struct state *const lclptr = &lclmem;
+static struct state *const gmtptr = &gmtmem;
+#endif /* State Farm */
+
+#ifndef TZ_STRLEN_MAX
+# define TZ_STRLEN_MAX 255
+#endif /* !defined TZ_STRLEN_MAX */
+
+static char		lcl_TZname[TZ_STRLEN_MAX + 1];
+static int		lcl_is_set;
+
+static pthread_once_t	gmt_once = PTHREAD_ONCE_INIT;
+static pthread_once_t	gmtime_once = PTHREAD_ONCE_INIT;
+static pthread_key_t	gmtime_key;
+static int		gmtime_key_error;
+static pthread_once_t	localtime_once = PTHREAD_ONCE_INIT;
+static pthread_key_t	localtime_key;
+static int		localtime_key_error;
+
+/*
+** Section 4.12.3 of X3.159-1989 requires that
+**	Except for the strftime function, these functions [asctime,
+**	ctime, gmtime, localtime] return values in one of two static
+**	objects: a broken-down time structure and an array of char.
+** Thanks to Paul Eggert for noting this.
+*/
+
+static struct tm	tm;
+
+#if 2 <= HAVE_TZNAME + TZ_TIME_T
+char *			tzname[2] = {
+	(char *) wildabbr,
+	(char *) wildabbr
+};
+#endif
+#if 2 <= USG_COMPAT + TZ_TIME_T
+long			timezone;
+int			daylight;
+#endif
+#if 2 <= ALTZONE + TZ_TIME_T
+long			altzone;
+#endif
+
+/* Initialize *S to a value based on UTOFF, ISDST, and DESIGIDX.  */
+static void
+init_ttinfo(struct ttinfo *s, int_fast32_t utoff, bool isdst, int desigidx)
+{
+  s->tt_utoff = utoff;
+  s->tt_isdst = isdst;
+  s->tt_desigidx = desigidx;
+  s->tt_ttisstd = false;
+  s->tt_ttisut = false;
+}
+
+/* Return true if SP's time type I does not specify local time.  */
+static bool
+ttunspecified(struct state const *sp, int i)
+{
+  char const *abbr = &sp->chars[sp->ttis[i].tt_desigidx];
+  /* memcmp is likely faster than strcmp, and is safe due to CHARS_EXTRA.  */
+  return memcmp(abbr, UNSPEC, sizeof UNSPEC) == 0;
+}
+
+static int_fast32_t
+detzcode(const char *const codep)
+{
+	register int_fast32_t	result;
+	register int		i;
+	int_fast32_t one = 1;
+	int_fast32_t halfmaxval = one << (32 - 2);
+	int_fast32_t maxval = halfmaxval - 1 + halfmaxval;
+	int_fast32_t minval = -1 - maxval;
+
+	result = codep[0] & 0x7f;
+	for (i = 1; i < 4; ++i)
+		result = (result << 8) | (codep[i] & 0xff);
+
+	if (codep[0] & 0x80) {
+	  /* Do two's-complement negation even on non-two's-complement machines.
+	     If the result would be minval - 1, return minval.  */
+	  result -= !TWOS_COMPLEMENT(int_fast32_t) && result != 0;
+	  result += minval;
+	}
+	return result;
+}
+
+static int_fast64_t
+detzcode64(const char *const codep)
+{
+	register int_fast64_t result;
+	register int	i;
+	int_fast64_t one = 1;
+	int_fast64_t halfmaxval = one << (64 - 2);
+	int_fast64_t maxval = halfmaxval - 1 + halfmaxval;
+	int_fast64_t minval = -TWOS_COMPLEMENT(int_fast64_t) - maxval;
+
+	result = codep[0] & 0x7f;
+	for (i = 1; i < 8; ++i)
+		result = (result << 8) | (codep[i] & 0xff);
+
+	if (codep[0] & 0x80) {
+	  /* Do two's-complement negation even on non-two's-complement machines.
+	     If the result would be minval - 1, return minval.  */
+	  result -= !TWOS_COMPLEMENT(int_fast64_t) && result != 0;
+	  result += minval;
+	}
+	return result;
+}
+
+static void
+update_tzname_etc(struct state const *sp, struct ttinfo const *ttisp)
+{
+#if HAVE_TZNAME
+  tzname[ttisp->tt_isdst] = (char *) &sp->chars[ttisp->tt_desigidx];
+#endif
+#if USG_COMPAT
+  if (!ttisp->tt_isdst)
+    timezone = - ttisp->tt_utoff;
+#endif
+#if ALTZONE
+  if (ttisp->tt_isdst)
+    altzone = - ttisp->tt_utoff;
+#endif
+}
+
+/* If STDDST_MASK indicates that SP's TYPE provides useful info,
+   update tzname, timezone, and/or altzone and return STDDST_MASK,
+   diminished by the provided info if it is a specified local time.
+   Otherwise, return STDDST_MASK.  See settzname for STDDST_MASK.  */
+static int
+may_update_tzname_etc(int stddst_mask, struct state *sp, int type)
+{
+  struct ttinfo *ttisp = &sp->ttis[type];
+  int this_bit = 1 << ttisp->tt_isdst;
+  if (stddst_mask & this_bit) {
+    update_tzname_etc(sp, ttisp);
+    if (!ttunspecified(sp, type))
+      return stddst_mask & ~this_bit;
+  }
+  return stddst_mask;
+}
+
+static void
+settzname(void)
+{
+	register struct state * const	sp = lclptr;
+	register int			i;
+
+	/* If STDDST_MASK & 1 we need info about a standard time.
+	   If STDDST_MASK & 2 we need info about a daylight saving time.
+	   When STDDST_MASK becomes zero we can stop looking.  */
+	int stddst_mask = 0;
+
+#if HAVE_TZNAME
+	tzname[0] = tzname[1] = (char *) (sp ? wildabbr : utc);
+	stddst_mask = 3;
+#endif
+#if USG_COMPAT
+	timezone = 0;
+	stddst_mask = 3;
+#endif
+#if ALTZONE
+	altzone = 0;
+	stddst_mask |= 2;
+#endif
+	/*
+	** And to get the latest time zone abbreviations into tzname. . .
+	*/
+	if (sp) {
+	  for (i = sp->timecnt - 1; stddst_mask && 0 <= i; i--)
+	    stddst_mask = may_update_tzname_etc(stddst_mask, sp, sp->types[i]);
+	  for (i = sp->typecnt - 1; stddst_mask && 0 <= i; i--)
+	    stddst_mask = may_update_tzname_etc(stddst_mask, sp, i);
+	}
+#if USG_COMPAT
+	daylight = stddst_mask >> 1 ^ 1;
+#endif
+}
+
+static void
+scrub_abbrs(struct state *sp)
+{
+	int i;
+	/*
+	** First, replace bogus characters.
+	*/
+	for (i = 0; i < sp->charcnt; ++i)
+		if (strchr(TZ_ABBR_CHAR_SET, sp->chars[i]) == NULL)
+			sp->chars[i] = TZ_ABBR_ERR_CHAR;
+	/*
+	** Second, truncate long abbreviations.
+	*/
+	for (i = 0; i < sp->typecnt; ++i) {
+		register const struct ttinfo * const	ttisp = &sp->ttis[i];
+		char *cp = &sp->chars[ttisp->tt_desigidx];
+
+		if (strlen(cp) > TZ_ABBR_MAX_LEN &&
+			strcmp(cp, GRANDPARENTED) != 0)
+				*(cp + TZ_ABBR_MAX_LEN) = '\0';
+	}
+}
+
+#ifdef DETECT_TZ_CHANGES
+/*
+ * Determine if there's a change in the timezone since the last time we checked.
+ * Returns: -1 on error
+ * 	     0 if the timezone has not changed
+ *	     1 if the timezone has changed
+ */
+static int
+change_in_tz(const char *name)
+{
+	static char old_name[PATH_MAX];
+	static struct stat old_sb;
+	struct stat sb;
+	int error;
+
+	error = stat(name, &sb);
+	if (error != 0)
+		return -1;
+
+	if (strcmp(name, old_name) != 0) {
+		strlcpy(old_name, name, sizeof(old_name));
+		old_sb = sb;
+		return 1;
+	}
+
+	if (sb.st_dev != old_sb.st_dev ||
+	    sb.st_ino != old_sb.st_ino ||
+	    sb.st_ctime != old_sb.st_ctime ||
+	    sb.st_mtime != old_sb.st_mtime) {
+		old_sb = sb;
+		return 1;
+	}
+
+	return 0;
+}
+#else /* !DETECT_TZ_CHANGES */
+#define	change_in_tz(X)	1
+#endif /* !DETECT_TZ_CHANGES */
+
+/* Input buffer for data read from a compiled tz file.  */
+union input_buffer {
+  /* The first part of the buffer, interpreted as a header.  */
+  struct tzhead tzhead;
+
+  /* The entire buffer.  */
+  char buf[2 * sizeof(struct tzhead) + 2 * sizeof(struct state)
+	   + 4 * TZ_MAX_TIMES];
+};
+
+/* TZDIR with a trailing '/' rather than a trailing '\0'.  */
+static char const tzdirslash[sizeof TZDIR] = TZDIR "/";
+
+/* Local storage needed for 'tzloadbody'.  */
+union local_storage {
+  /* The results of analyzing the file's contents after it is opened.  */
+  struct file_analysis {
+    /* The input buffer.  */
+    union input_buffer u;
+
+    /* A temporary state used for parsing a TZ string in the file.  */
+    struct state st;
+  } u;
+
+  /* The file name to be opened.  */
+  char fullname[max(sizeof(struct file_analysis), sizeof tzdirslash + 1024)];
+};
+
+/* Load tz data from the file named NAME into *SP.  Read extended
+   format if DOEXTEND.  Use *LSP for temporary storage.  Return 0 on
+   success, an errno value on failure.  */
+static int
+tzloadbody(char const *name, struct state *sp, bool doextend,
+	   union local_storage *lsp)
+{
+	register int			i;
+	register int			fid;
+	register int			stored;
+	register ssize_t		nread;
+	register bool doaccess;
+	register union input_buffer *up = &lsp->u.u;
+	register int tzheadsize = sizeof(struct tzhead);
+
+	sp->goback = sp->goahead = false;
+
+	if (! name) {
+		name = TZDEFAULT;
+		if (! name)
+		  return EINVAL;
+	}
+
+	if (name[0] == ':')
+		++name;
+#ifdef SUPPRESS_TZDIR
+	/* Do not prepend TZDIR.  This is intended for specialized
+	   applications only, due to its security implications.  */
+	doaccess = true;
+#else
+	doaccess = name[0] == '/';
+#endif
+	if (!doaccess) {
+		char const *dot;
+		if (sizeof lsp->fullname - sizeof tzdirslash <= strlen(name))
+		  return ENAMETOOLONG;
+
+		/* Create a string "TZDIR/NAME".  Using sprintf here
+		   would pull in stdio (and would fail if the
+		   resulting string length exceeded INT_MAX!).  */
+		memcpy(lsp->fullname, tzdirslash, sizeof tzdirslash);
+		strcpy(lsp->fullname + sizeof tzdirslash, name);
+
+		/* Set doaccess if NAME contains a ".." file name
+		   component, as such a name could read a file outside
+		   the TZDIR virtual subtree.  */
+		for (dot = name; (dot = strchr(dot, '.')); dot++)
+		  if ((dot == name || dot[-1] == '/') && dot[1] == '.'
+		      && (dot[2] == '/' || !dot[2])) {
+		    doaccess = true;
+		    break;
+		  }
+
+		name = lsp->fullname;
+	}
+	if (doaccess && access(name, R_OK) != 0)
+	  return errno;
+	if (doextend) {
+		/*
+		 * Detect if the timezone file has changed.  Check
+		 * 'doextend' to ignore TZDEFRULES; the change_in_tz()
+		 * function can only keep state for a single file.
+		 */
+		int ret = change_in_tz(name);
+		if (ret <= 0) {
+			/*
+			 * Returns an errno value if there was an error,
+			 * and 0 if the timezone had not changed.
+			 */
+			return errno;
+		}
+	}
+	fid = _open(name, O_RDONLY | O_BINARY);
+	if (fid < 0)
+	  return errno;
+
+	nread = _read(fid, up->buf, sizeof up->buf);
+	if (nread < tzheadsize) {
+	  int err = nread < 0 ? errno : EINVAL;
+	  _close(fid);
+	  return err;
+	}
+	if (_close(fid) < 0)
+	  return errno;
+	for (stored = 4; stored <= 8; stored *= 2) {
+	    char version = up->tzhead.tzh_version[0];
+	    bool skip_datablock = stored == 4 && version;
+	    int_fast32_t datablock_size;
+	    int_fast32_t ttisstdcnt = detzcode(up->tzhead.tzh_ttisstdcnt);
+	    int_fast32_t ttisutcnt = detzcode(up->tzhead.tzh_ttisutcnt);
+	    int_fast64_t prevtr = -1;
+	    int_fast32_t prevcorr;
+	    int_fast32_t leapcnt = detzcode(up->tzhead.tzh_leapcnt);
+	    int_fast32_t timecnt = detzcode(up->tzhead.tzh_timecnt);
+	    int_fast32_t typecnt = detzcode(up->tzhead.tzh_typecnt);
+	    int_fast32_t charcnt = detzcode(up->tzhead.tzh_charcnt);
+	    char const *p = up->buf + tzheadsize;
+	    /* Although tzfile(5) currently requires typecnt to be nonzero,
+	       support future formats that may allow zero typecnt
+	       in files that have a TZ string and no transitions.  */
+	    if (! (0 <= leapcnt && leapcnt < TZ_MAX_LEAPS
+		   && 0 <= typecnt && typecnt < TZ_MAX_TYPES
+		   && 0 <= timecnt && timecnt < TZ_MAX_TIMES
+		   && 0 <= charcnt && charcnt < TZ_MAX_CHARS
+		   && 0 <= ttisstdcnt && ttisstdcnt < TZ_MAX_TYPES
+		   && 0 <= ttisutcnt && ttisutcnt < TZ_MAX_TYPES))
+	      return EINVAL;
+	    datablock_size
+		    = (timecnt * stored		/* ats */
+		       + timecnt		/* types */
+		       + typecnt * 6		/* ttinfos */
+		       + charcnt		/* chars */
+		       + leapcnt * (stored + 4)	/* lsinfos */
+		       + ttisstdcnt		/* ttisstds */
+		       + ttisutcnt);		/* ttisuts */
+	    if (nread < tzheadsize + datablock_size)
+	      return EINVAL;
+	    if (skip_datablock)
+		p += datablock_size;
+	    else {
+		if (! ((ttisstdcnt == typecnt || ttisstdcnt == 0)
+		       && (ttisutcnt == typecnt || ttisutcnt == 0)))
+		  return EINVAL;
+
+		sp->leapcnt = leapcnt;
+		sp->timecnt = timecnt;
+		sp->typecnt = typecnt;
+		sp->charcnt = charcnt;
+
+		/* Read transitions, discarding those out of time_t range.
+		   But pretend the last transition before TIME_T_MIN
+		   occurred at TIME_T_MIN.  */
+		timecnt = 0;
+		for (i = 0; i < sp->timecnt; ++i) {
+			int_fast64_t at
+			  = stored == 4 ? detzcode(p) : detzcode64(p);
+			sp->types[i] = at <= TIME_T_MAX;
+			if (sp->types[i]) {
+			  time_t attime
+			    = ((TYPE_SIGNED(time_t) ? at < TIME_T_MIN : at < 0)
+			       ? TIME_T_MIN : at);
+			  if (timecnt && attime <= sp->ats[timecnt - 1]) {
+			    if (attime < sp->ats[timecnt - 1])
+			      return EINVAL;
+			    sp->types[i - 1] = 0;
+			    timecnt--;
+			  }
+			  sp->ats[timecnt++] = attime;
+			}
+			p += stored;
+		}
+
+		timecnt = 0;
+		for (i = 0; i < sp->timecnt; ++i) {
+			unsigned char typ = *p++;
+			if (sp->typecnt <= typ)
+			  return EINVAL;
+			if (sp->types[i])
+				sp->types[timecnt++] = typ;
+		}
+		sp->timecnt = timecnt;
+		for (i = 0; i < sp->typecnt; ++i) {
+			register struct ttinfo *	ttisp;
+			unsigned char isdst, desigidx;
+
+			ttisp = &sp->ttis[i];
+			ttisp->tt_utoff = detzcode(p);
+			p += 4;
+			isdst = *p++;
+			if (! (isdst < 2))
+			  return EINVAL;
+			ttisp->tt_isdst = isdst;
+			desigidx = *p++;
+			if (! (desigidx < sp->charcnt))
+			  return EINVAL;
+			ttisp->tt_desigidx = desigidx;
+		}
+		for (i = 0; i < sp->charcnt; ++i)
+			sp->chars[i] = *p++;
+		/* Ensure '\0'-terminated, and make it safe to call
+		   ttunspecified later.  */
+		memset(&sp->chars[i], 0, CHARS_EXTRA);
+
+		/* Read leap seconds, discarding those out of time_t range.  */
+		leapcnt = 0;
+		for (i = 0; i < sp->leapcnt; ++i) {
+		  int_fast64_t tr = stored == 4 ? detzcode(p) : detzcode64(p);
+		  int_fast32_t corr = detzcode(p + stored);
+		  p += stored + 4;
+
+		  /* Leap seconds cannot occur before the Epoch,
+		     or out of order.  */
+		  if (tr <= prevtr)
+		    return EINVAL;
+
+		  /* To avoid other botches in this code, each leap second's
+		     correction must differ from the previous one's by 1
+		     second or less, except that the first correction can be
+		     any value; these requirements are more generous than
+		     RFC 8536, to allow future RFC extensions.  */
+		  if (! (i == 0
+			 || (prevcorr < corr
+			     ? corr == prevcorr + 1
+			     : (corr == prevcorr
+				|| corr == prevcorr - 1))))
+		    return EINVAL;
+		  prevtr = tr;
+		  prevcorr = corr;
+
+		  if (tr <= TIME_T_MAX) {
+		    sp->lsis[leapcnt].ls_trans = tr;
+		    sp->lsis[leapcnt].ls_corr = corr;
+		    leapcnt++;
+		  }
+		}
+		sp->leapcnt = leapcnt;
+
+		for (i = 0; i < sp->typecnt; ++i) {
+			register struct ttinfo *	ttisp;
+
+			ttisp = &sp->ttis[i];
+			if (ttisstdcnt == 0)
+				ttisp->tt_ttisstd = false;
+			else {
+				if (*p != true && *p != false)
+				  return EINVAL;
+				ttisp->tt_ttisstd = *p++;
+			}
+		}
+		for (i = 0; i < sp->typecnt; ++i) {
+			register struct ttinfo *	ttisp;
+
+			ttisp = &sp->ttis[i];
+			if (ttisutcnt == 0)
+				ttisp->tt_ttisut = false;
+			else {
+				if (*p != true && *p != false)
+						return EINVAL;
+				ttisp->tt_ttisut = *p++;
+			}
+		}
+	    }
+
+	    nread -= p - up->buf;
+	    memmove(up->buf, p, nread);
+
+	    /* If this is an old file, we're done.  */
+	    if (!version)
+	      break;
+	}
+	if (doextend && nread > 2 &&
+		up->buf[0] == '\n' && up->buf[nread - 1] == '\n' &&
+		sp->typecnt + 2 <= TZ_MAX_TYPES) {
+			struct state	*ts = &lsp->u.st;
+
+			up->buf[nread - 1] = '\0';
+			if (tzparse(&up->buf[1], ts, sp)) {
+
+			  /* Attempt to reuse existing abbreviations.
+			     Without this, America/Anchorage would be right on
+			     the edge after 2037 when TZ_MAX_CHARS is 50, as
+			     sp->charcnt equals 40 (for LMT AST AWT APT AHST
+			     AHDT YST AKDT AKST) and ts->charcnt equals 10
+			     (for AKST AKDT).  Reusing means sp->charcnt can
+			     stay 40 in this example.  */
+			  int gotabbr = 0;
+			  int charcnt = sp->charcnt;
+			  for (i = 0; i < ts->typecnt; i++) {
+			    char *tsabbr = ts->chars + ts->ttis[i].tt_desigidx;
+			    int j;
+			    for (j = 0; j < charcnt; j++)
+			      if (strcmp(sp->chars + j, tsabbr) == 0) {
+				ts->ttis[i].tt_desigidx = j;
+				gotabbr++;
+				break;
+			      }
+			    if (! (j < charcnt)) {
+			      int tsabbrlen = strlen(tsabbr);
+			      if (j + tsabbrlen < TZ_MAX_CHARS) {
+				strcpy(sp->chars + j, tsabbr);
+				charcnt = j + tsabbrlen + 1;
+				ts->ttis[i].tt_desigidx = j;
+				gotabbr++;
+			      }
+			    }
+			  }
+			  if (gotabbr == ts->typecnt) {
+			    sp->charcnt = charcnt;
+
+			    /* Ignore any trailing, no-op transitions generated
+			       by zic as they don't help here and can run afoul
+			       of bugs in zic 2016j or earlier.  */
+			    while (1 < sp->timecnt
+				   && (sp->types[sp->timecnt - 1]
+				       == sp->types[sp->timecnt - 2]))
+			      sp->timecnt--;
+
+			    for (i = 0;
+				 i < ts->timecnt && sp->timecnt < TZ_MAX_TIMES;
+				 i++) {
+			      time_t t = ts->ats[i];
+			      if (increment_overflow_time(&t, leapcorr(sp, t))
+				  || (0 < sp->timecnt
+				      && t <= sp->ats[sp->timecnt - 1]))
+				continue;
+			      sp->ats[sp->timecnt] = t;
+			      sp->types[sp->timecnt] = (sp->typecnt
+							+ ts->types[i]);
+			      sp->timecnt++;
+			    }
+			    for (i = 0; i < ts->typecnt; i++)
+			      sp->ttis[sp->typecnt++] = ts->ttis[i];
+			  }
+			}
+	}
+	if (sp->typecnt == 0)
+	  return EINVAL;
+	if (sp->timecnt > 1) {
+	    if (sp->ats[0] <= TIME_T_MAX - SECSPERREPEAT) {
+		time_t repeatat = sp->ats[0] + SECSPERREPEAT;
+		int repeattype = sp->types[0];
+		for (i = 1; i < sp->timecnt; ++i)
+		  if (sp->ats[i] == repeatat
+		      && typesequiv(sp, sp->types[i], repeattype)) {
+					sp->goback = true;
+					break;
+		  }
+	    }
+	    if (TIME_T_MIN + SECSPERREPEAT <= sp->ats[sp->timecnt - 1]) {
+		time_t repeatat = sp->ats[sp->timecnt - 1] - SECSPERREPEAT;
+		int repeattype = sp->types[sp->timecnt - 1];
+		for (i = sp->timecnt - 2; i >= 0; --i)
+		  if (sp->ats[i] == repeatat
+		      && typesequiv(sp, sp->types[i], repeattype)) {
+					sp->goahead = true;
+					break;
+		  }
+	    }
+	}
+
+	/* Infer sp->defaulttype from the data.  Although this default
+	   type is always zero for data from recent tzdb releases,
+	   things are trickier for data from tzdb 2018e or earlier.
+
+	   The first set of heuristics work around bugs in 32-bit data
+	   generated by tzdb 2013c or earlier.  The workaround is for
+	   zones like Australia/Macquarie where timestamps before the
+	   first transition have a time type that is not the earliest
+	   standard-time type.  See:
+	   https://mm.icann.org/pipermail/tz/2013-May/019368.html */
+	/*
+	** If type 0 does not specify local time, or is unused in transitions,
+	** it's the type to use for early times.
+	*/
+	for (i = 0; i < sp->timecnt; ++i)
+		if (sp->types[i] == 0)
+			break;
+	i = i < sp->timecnt && ! ttunspecified(sp, 0) ? -1 : 0;
+	/*
+	** Absent the above,
+	** if there are transition times
+	** and the first transition is to a daylight time
+	** find the standard type less than and closest to
+	** the type of the first transition.
+	*/
+	if (i < 0 && sp->timecnt > 0 && sp->ttis[sp->types[0]].tt_isdst) {
+		i = sp->types[0];
+		while (--i >= 0)
+			if (!sp->ttis[i].tt_isdst)
+				break;
+	}
+	/* The next heuristics are for data generated by tzdb 2018e or
+	   earlier, for zones like EST5EDT where the first transition
+	   is to DST.  */
+	/*
+	** If no result yet, find the first standard type.
+	** If there is none, punt to type zero.
+	*/
+	if (i < 0) {
+		i = 0;
+		while (sp->ttis[i].tt_isdst)
+			if (++i >= sp->typecnt) {
+				i = 0;
+				break;
+			}
+	}
+	/* A simple 'sp->defaulttype = 0;' would suffice here if we
+	   didn't have to worry about 2018e-or-earlier data.  Even
+	   simpler would be to remove the defaulttype member and just
+	   use 0 in its place.  */
+	sp->defaulttype = i;
+
+	return 0;
+}
+
+/* Load tz data from the file named NAME into *SP.  Read extended
+   format if DOEXTEND.  Return 0 on success, an errno value on failure.  */
+static int
+tzload(char const *name, struct state *sp, bool doextend)
+{
+#ifdef ALL_STATE
+  union local_storage *lsp = malloc(sizeof *lsp);
+  if (!lsp) {
+    return HAVE_MALLOC_ERRNO ? errno : ENOMEM;
+  } else {
+    int err = tzloadbody(name, sp, doextend, lsp);
+    free(lsp);
+    return err;
+  }
+#else
+  union local_storage ls;
+  return tzloadbody(name, sp, doextend, &ls);
+#endif
+}
+
+static bool
+typesequiv(const struct state *sp, int a, int b)
+{
+	register bool result;
+
+	if (sp == NULL ||
+		a < 0 || a >= sp->typecnt ||
+		b < 0 || b >= sp->typecnt)
+			result = false;
+	else {
+		/* Compare the relevant members of *AP and *BP.
+		   Ignore tt_ttisstd and tt_ttisut, as they are
+		   irrelevant now and counting them could cause
+		   sp->goahead to mistakenly remain false.  */
+		register const struct ttinfo *	ap = &sp->ttis[a];
+		register const struct ttinfo *	bp = &sp->ttis[b];
+		result = (ap->tt_utoff == bp->tt_utoff
+			  && ap->tt_isdst == bp->tt_isdst
+			  && (strcmp(&sp->chars[ap->tt_desigidx],
+				     &sp->chars[bp->tt_desigidx])
+			      == 0));
+	}
+	return result;
+}
+
+static const int	mon_lengths[2][MONSPERYEAR] = {
+	{ 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 },
+	{ 31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 }
+};
+
+static const int	year_lengths[2] = {
+	DAYSPERNYEAR, DAYSPERLYEAR
+};
+
+/* Is C an ASCII digit?  */
+static bool
+is_digit(char c)
+{
+  return '0' <= c && c <= '9';
+}
+
+/*
+** Given a pointer into a timezone string, scan until a character that is not
+** a valid character in a time zone abbreviation is found.
+** Return a pointer to that character.
+*/
+
+static ATTRIBUTE_REPRODUCIBLE const char *
+getzname(register const char *strp)
+{
+	register char	c;
+
+	while ((c = *strp) != '\0' && !is_digit(c) && c != ',' && c != '-' &&
+		c != '+')
+			++strp;
+	return strp;
+}
+
+/*
+** Given a pointer into an extended timezone string, scan until the ending
+** delimiter of the time zone abbreviation is located.
+** Return a pointer to the delimiter.
+**
+** As with getzname above, the legal character set is actually quite
+** restricted, with other characters producing undefined results.
+** We don't do any checking here; checking is done later in common-case code.
+*/
+
+static ATTRIBUTE_REPRODUCIBLE const char *
+getqzname(register const char *strp, const int delim)
+{
+	register int	c;
+
+	while ((c = *strp) != '\0' && c != delim)
+		++strp;
+	return strp;
+}
+
+/*
+** Given a pointer into a timezone string, extract a number from that string.
+** Check that the number is within a specified range; if it is not, return
+** NULL.
+** Otherwise, return a pointer to the first character not part of the number.
+*/
+
+static const char *
+getnum(register const char *strp, int *const nump, const int min, const int max)
+{
+	register char	c;
+	register int	num;
+
+	if (strp == NULL || !is_digit(c = *strp))
+		return NULL;
+	num = 0;
+	do {
+		num = num * 10 + (c - '0');
+		if (num > max)
+			return NULL;	/* illegal value */
+		c = *++strp;
+	} while (is_digit(c));
+	if (num < min)
+		return NULL;		/* illegal value */
+	*nump = num;
+	return strp;
+}
+
+/*
+** Given a pointer into a timezone string, extract a number of seconds,
+** in hh[:mm[:ss]] form, from the string.
+** If any error occurs, return NULL.
+** Otherwise, return a pointer to the first character not part of the number
+** of seconds.
+*/
+
+static const char *
+getsecs(register const char *strp, int_fast32_t *const secsp)
+{
+	int	num;
+	int_fast32_t secsperhour = SECSPERHOUR;
+
+	/*
+	** 'HOURSPERDAY * DAYSPERWEEK - 1' allows quasi-Posix rules like
+	** "M10.4.6/26", which does not conform to Posix,
+	** but which specifies the equivalent of
+	** "02:00 on the first Sunday on or after 23 Oct".
+	*/
+	strp = getnum(strp, &num, 0, HOURSPERDAY * DAYSPERWEEK - 1);
+	if (strp == NULL)
+		return NULL;
+	*secsp = num * secsperhour;
+	if (*strp == ':') {
+		++strp;
+		strp = getnum(strp, &num, 0, MINSPERHOUR - 1);
+		if (strp == NULL)
+			return NULL;
+		*secsp += num * SECSPERMIN;
+		if (*strp == ':') {
+			++strp;
+			/* 'SECSPERMIN' allows for leap seconds.  */
+			strp = getnum(strp, &num, 0, SECSPERMIN);
+			if (strp == NULL)
+				return NULL;
+			*secsp += num;
+		}
+	}
+	return strp;
+}
+
+/*
+** Given a pointer into a timezone string, extract an offset, in
+** [+-]hh[:mm[:ss]] form, from the string.
+** If any error occurs, return NULL.
+** Otherwise, return a pointer to the first character not part of the time.
+*/
+
+static const char *
+getoffset(register const char *strp, int_fast32_t *const offsetp)
+{
+	register bool neg = false;
+
+	if (*strp == '-') {
+		neg = true;
+		++strp;
+	} else if (*strp == '+')
+		++strp;
+	strp = getsecs(strp, offsetp);
+	if (strp == NULL)
+		return NULL;		/* illegal time */
+	if (neg)
+		*offsetp = -*offsetp;
+	return strp;
+}
+
+/*
+** Given a pointer into a timezone string, extract a rule in the form
+** date[/time]. See POSIX section 8 for the format of "date" and "time".
+** If a valid rule is not found, return NULL.
+** Otherwise, return a pointer to the first character not part of the rule.
+*/
+
+static const char *
+getrule(const char *strp, register struct rule *const rulep)
+{
+	if (*strp == 'J') {
+		/*
+		** Julian day.
+		*/
+		rulep->r_type = JULIAN_DAY;
+		++strp;
+		strp = getnum(strp, &rulep->r_day, 1, DAYSPERNYEAR);
+	} else if (*strp == 'M') {
+		/*
+		** Month, week, day.
+		*/
+		rulep->r_type = MONTH_NTH_DAY_OF_WEEK;
+		++strp;
+		strp = getnum(strp, &rulep->r_mon, 1, MONSPERYEAR);
+		if (strp == NULL)
+			return NULL;
+		if (*strp++ != '.')
+			return NULL;
+		strp = getnum(strp, &rulep->r_week, 1, 5);
+		if (strp == NULL)
+			return NULL;
+		if (*strp++ != '.')
+			return NULL;
+		strp = getnum(strp, &rulep->r_day, 0, DAYSPERWEEK - 1);
+	} else if (is_digit(*strp)) {
+		/*
+		** Day of year.
+		*/
+		rulep->r_type = DAY_OF_YEAR;
+		strp = getnum(strp, &rulep->r_day, 0, DAYSPERLYEAR - 1);
+	} else	return NULL;		/* invalid format */
+	if (strp == NULL)
+		return NULL;
+	if (*strp == '/') {
+		/*
+		** Time specified.
+		*/
+		++strp;
+		strp = getoffset(strp, &rulep->r_time);
+	} else	rulep->r_time = 2 * SECSPERHOUR;	/* default = 2:00:00 */
+	return strp;
+}
+
+/*
+** Given a year, a rule, and the offset from UT at the time that rule takes
+** effect, calculate the year-relative time that rule takes effect.
+*/
+
+static int_fast32_t
+transtime(const int year, register const struct rule *const rulep,
+	  const int_fast32_t offset)
+{
+	register bool	leapyear;
+	register int_fast32_t value;
+	register int	i;
+	int		d, m1, yy0, yy1, yy2, dow;
+
+	leapyear = isleap(year);
+	switch (rulep->r_type) {
+
+	case JULIAN_DAY:
+		/*
+		** Jn - Julian day, 1 == January 1, 60 == March 1 even in leap
+		** years.
+		** In non-leap years, or if the day number is 59 or less, just
+		** add SECSPERDAY times the day number-1 to the time of
+		** January 1, midnight, to get the day.
+		*/
+		value = (rulep->r_day - 1) * SECSPERDAY;
+		if (leapyear && rulep->r_day >= 60)
+			value += SECSPERDAY;
+		break;
+
+	case DAY_OF_YEAR:
+		/*
+		** n - day of year.
+		** Just add SECSPERDAY times the day number to the time of
+		** January 1, midnight, to get the day.
+		*/
+		value = rulep->r_day * SECSPERDAY;
+		break;
+
+	case MONTH_NTH_DAY_OF_WEEK:
+		/*
+		** Mm.n.d - nth "dth day" of month m.
+		*/
+
+		/*
+		** Use Zeller's Congruence to get day-of-week of first day of
+		** month.
+		*/
+		m1 = (rulep->r_mon + 9) % 12 + 1;
+		yy0 = (rulep->r_mon <= 2) ? (year - 1) : year;
+		yy1 = yy0 / 100;
+		yy2 = yy0 % 100;
+		dow = ((26 * m1 - 2) / 10 +
+			1 + yy2 + yy2 / 4 + yy1 / 4 - 2 * yy1) % 7;
+		if (dow < 0)
+			dow += DAYSPERWEEK;
+
+		/*
+		** "dow" is the day-of-week of the first day of the month. Get
+		** the day-of-month (zero-origin) of the first "dow" day of the
+		** month.
+		*/
+		d = rulep->r_day - dow;
+		if (d < 0)
+			d += DAYSPERWEEK;
+		for (i = 1; i < rulep->r_week; ++i) {
+			if (d + DAYSPERWEEK >=
+				mon_lengths[leapyear][rulep->r_mon - 1])
+					break;
+			d += DAYSPERWEEK;
+		}
+
+		/*
+		** "d" is the day-of-month (zero-origin) of the day we want.
+		*/
+		value = d * SECSPERDAY;
+		for (i = 0; i < rulep->r_mon - 1; ++i)
+			value += mon_lengths[leapyear][i] * SECSPERDAY;
+		break;
+
+	default: unreachable();
+	}
+
+	/*
+	** "value" is the year-relative time of 00:00:00 UT on the day in
+	** question. To get the year-relative time of the specified local
+	** time on that day, add the transition time and the current offset
+	** from UT.
+	*/
+	return value + rulep->r_time + offset;
+}
+
+/*
+** Given a POSIX section 8-style TZ string, fill in the rule tables as
+** appropriate.
+*/
+
+static bool
+tzparse(const char *name, struct state *sp, struct state *basep)
+{
+	const char *			stdname;
+	const char *			dstname;
+	int_fast32_t			stdoffset;
+	int_fast32_t			dstoffset;
+	register char *			cp;
+	register bool			load_ok;
+	ptrdiff_t stdlen, dstlen, charcnt;
+	time_t atlo = TIME_T_MIN, leaplo = TIME_T_MIN;
+
+	stdname = name;
+	if (*name == '<') {
+	  name++;
+	  stdname = name;
+	  name = getqzname(name, '>');
+	  if (*name != '>')
+	    return false;
+	  stdlen = name - stdname;
+	  name++;
+	} else {
+	  name = getzname(name);
+	  stdlen = name - stdname;
+	}
+	if (!stdlen)
+	  return false;
+	name = getoffset(name, &stdoffset);
+	if (name == NULL)
+	  return false;
+	charcnt = stdlen + 1;
+	if (sizeof sp->chars < charcnt)
+	  return false;
+	if (basep) {
+	  if (0 < basep->timecnt)
+	    atlo = basep->ats[basep->timecnt - 1];
+	  load_ok = false;
+	  sp->leapcnt = basep->leapcnt;
+	  memcpy(sp->lsis, basep->lsis, sp->leapcnt * sizeof *sp->lsis);
+	} else {
+	  load_ok = tzload(TZDEFRULES, sp, false) == 0;
+	  if (!load_ok)
+	    sp->leapcnt = 0;	/* So, we're off a little.  */
+	}
+	if (0 < sp->leapcnt)
+	  leaplo = sp->lsis[sp->leapcnt - 1].ls_trans;
+	if (*name != '\0') {
+		if (*name == '<') {
+			dstname = ++name;
+			name = getqzname(name, '>');
+			if (*name != '>')
+			  return false;
+			dstlen = name - dstname;
+			name++;
+		} else {
+			dstname = name;
+			name = getzname(name);
+			dstlen = name - dstname; /* length of DST abbr. */
+		}
+		if (!dstlen)
+		  return false;
+		charcnt += dstlen + 1;
+		if (sizeof sp->chars < charcnt)
+		  return false;
+		if (*name != '\0' && *name != ',' && *name != ';') {
+			name = getoffset(name, &dstoffset);
+			if (name == NULL)
+			  return false;
+		} else	dstoffset = stdoffset - SECSPERHOUR;
+		if (*name == '\0' && !load_ok)
+			name = TZDEFRULESTRING;
+		if (*name == ',' || *name == ';') {
+			struct rule	start;
+			struct rule	end;
+			register int	year;
+			register int	timecnt;
+			time_t		janfirst;
+			int_fast32_t janoffset = 0;
+			int yearbeg, yearlim;
+
+			++name;
+			if ((name = getrule(name, &start)) == NULL)
+			  return false;
+			if (*name++ != ',')
+			  return false;
+			if ((name = getrule(name, &end)) == NULL)
+			  return false;
+			if (*name != '\0')
+			  return false;
+			sp->typecnt = 2;	/* standard time and DST */
+			/*
+			** Two transitions per year, from EPOCH_YEAR forward.
+			*/
+			init_ttinfo(&sp->ttis[0], -stdoffset, false, 0);
+			init_ttinfo(&sp->ttis[1], -dstoffset, true, stdlen + 1);
+			sp->defaulttype = 0;
+			timecnt = 0;
+			janfirst = 0;
+			yearbeg = EPOCH_YEAR;
+
+			do {
+			  int_fast32_t yearsecs
+			    = year_lengths[isleap(yearbeg - 1)] * SECSPERDAY;
+			  yearbeg--;
+			  if (increment_overflow_time(&janfirst, -yearsecs)) {
+			    janoffset = -yearsecs;
+			    break;
+			  }
+			} while (atlo < janfirst
+				 && EPOCH_YEAR - YEARSPERREPEAT / 2 < yearbeg);
+
+			while (true) {
+			  int_fast32_t yearsecs
+			    = year_lengths[isleap(yearbeg)] * SECSPERDAY;
+			  int yearbeg1 = yearbeg;
+			  time_t janfirst1 = janfirst;
+			  if (increment_overflow_time(&janfirst1, yearsecs)
+			      || increment_overflow(&yearbeg1, 1)
+			      || atlo <= janfirst1)
+			    break;
+			  yearbeg = yearbeg1;
+			  janfirst = janfirst1;
+			}
+
+			yearlim = yearbeg;
+			if (increment_overflow(&yearlim, YEARSPERREPEAT + 1))
+			  yearlim = INT_MAX;
+			for (year = yearbeg; year < yearlim; year++) {
+				int_fast32_t
+				  starttime = transtime(year, &start, stdoffset),
+				  endtime = transtime(year, &end, dstoffset);
+				int_fast32_t
+				  yearsecs = (year_lengths[isleap(year)]
+					      * SECSPERDAY);
+				bool reversed = endtime < starttime;
+				if (reversed) {
+					int_fast32_t swap = starttime;
+					starttime = endtime;
+					endtime = swap;
+				}
+				if (reversed
+				    || (starttime < endtime
+					&& endtime - starttime < yearsecs)) {
+					if (TZ_MAX_TIMES - 2 < timecnt)
+						break;
+					sp->ats[timecnt] = janfirst;
+					if (! increment_overflow_time
+					    (&sp->ats[timecnt],
+					     janoffset + starttime)
+					    && atlo <= sp->ats[timecnt])
+					  sp->types[timecnt++] = !reversed;
+					sp->ats[timecnt] = janfirst;
+					if (! increment_overflow_time
+					    (&sp->ats[timecnt],
+					     janoffset + endtime)
+					    && atlo <= sp->ats[timecnt]) {
+					  sp->types[timecnt++] = reversed;
+					}
+				}
+				if (endtime < leaplo) {
+				  yearlim = year;
+				  if (increment_overflow(&yearlim,
+							 YEARSPERREPEAT + 1))
+				    yearlim = INT_MAX;
+				}
+				if (increment_overflow_time
+				    (&janfirst, janoffset + yearsecs))
+					break;
+				janoffset = 0;
+			}
+			sp->timecnt = timecnt;
+			if (! timecnt) {
+				sp->ttis[0] = sp->ttis[1];
+				sp->typecnt = 1;	/* Perpetual DST.  */
+			} else if (YEARSPERREPEAT < year - yearbeg)
+				sp->goback = sp->goahead = true;
+		} else {
+			register int_fast32_t	theirstdoffset;
+			register int_fast32_t	theirdstoffset;
+			register int_fast32_t	theiroffset;
+			register bool		isdst;
+			register int		i;
+			register int		j;
+
+			if (*name != '\0')
+			  return false;
+			/*
+			** Initial values of theirstdoffset and theirdstoffset.
+			*/
+			theirstdoffset = 0;
+			for (i = 0; i < sp->timecnt; ++i) {
+				j = sp->types[i];
+				if (!sp->ttis[j].tt_isdst) {
+					theirstdoffset =
+						- sp->ttis[j].tt_utoff;
+					break;
+				}
+			}
+			theirdstoffset = 0;
+			for (i = 0; i < sp->timecnt; ++i) {
+				j = sp->types[i];
+				if (sp->ttis[j].tt_isdst) {
+					theirdstoffset =
+						- sp->ttis[j].tt_utoff;
+					break;
+				}
+			}
+			/*
+			** Initially we're assumed to be in standard time.
+			*/
+			isdst = false;
+			/*
+			** Now juggle transition times and types
+			** tracking offsets as you do.
+			*/
+			for (i = 0; i < sp->timecnt; ++i) {
+				j = sp->types[i];
+				sp->types[i] = sp->ttis[j].tt_isdst;
+				if (sp->ttis[j].tt_ttisut) {
+					/* No adjustment to transition time */
+				} else {
+					/*
+					** If daylight saving time is in
+					** effect, and the transition time was
+					** not specified as standard time, add
+					** the daylight saving time offset to
+					** the transition time; otherwise, add
+					** the standard time offset to the
+					** transition time.
+					*/
+					/*
+					** Transitions from DST to DDST
+					** will effectively disappear since
+					** POSIX provides for only one DST
+					** offset.
+					*/
+					if (isdst && !sp->ttis[j].tt_ttisstd) {
+						sp->ats[i] += dstoffset -
+							theirdstoffset;
+					} else {
+						sp->ats[i] += stdoffset -
+							theirstdoffset;
+					}
+				}
+				theiroffset = -sp->ttis[j].tt_utoff;
+				if (sp->ttis[j].tt_isdst)
+					theirdstoffset = theiroffset;
+				else	theirstdoffset = theiroffset;
+			}
+			/*
+			** Finally, fill in ttis.
+			*/
+			init_ttinfo(&sp->ttis[0], -stdoffset, false, 0);
+			init_ttinfo(&sp->ttis[1], -dstoffset, true, stdlen + 1);
+			sp->typecnt = 2;
+			sp->defaulttype = 0;
+		}
+	} else {
+		dstlen = 0;
+		sp->typecnt = 1;		/* only standard time */
+		sp->timecnt = 0;
+		init_ttinfo(&sp->ttis[0], -stdoffset, false, 0);
+		sp->defaulttype = 0;
+	}
+	sp->charcnt = charcnt;
+	cp = sp->chars;
+	memcpy(cp, stdname, stdlen);
+	cp += stdlen;
+	*cp++ = '\0';
+	if (dstlen != 0) {
+		memcpy(cp, dstname, dstlen);
+		*(cp + dstlen) = '\0';
+	}
+	return true;
+}
+
+static void
+gmtload(struct state *const sp)
+{
+	if (tzload(etc_utc, sp, true) != 0)
+	  tzparse("UTC0", sp, NULL);
+}
+
+#ifdef DETECT_TZ_CHANGES
+static int
+recheck_tzdata()
+{
+	static time_t last_checked;
+	struct timespec now;
+	time_t current_time;
+	int error;
+
+	/*
+	 * We want to recheck the timezone file every 61 sec.
+	 */
+	error = clock_gettime(CLOCK_MONOTONIC, &now);
+	if (error < 0) {
+		/* XXX: Can we somehow report this? */
+		return 0;
+	}
+
+	current_time = now.tv_sec;
+	if ((current_time - last_checked > DETECT_TZ_CHANGES_INTERVAL) ||
+	    (last_checked > current_time)) {
+		last_checked = current_time;
+		return 1;
+	}
+
+	return 0;
+}
+#else /* !DETECT_TZ_CHANGES */
+#define	recheck_tzdata()	0
+#endif /* !DETECT_TZ_CHANGES */
+
+/* Initialize *SP to a value appropriate for the TZ setting NAME.
+   Return 0 on success, an errno value on failure.  */
+static int
+zoneinit(struct state *sp, char const *name)
+{
+  if (name && ! name[0]) {
+    /*
+    ** User wants it fast rather than right.
+    */
+    sp->leapcnt = 0;		/* so, we're off a little */
+    sp->timecnt = 0;
+    sp->typecnt = 0;
+    sp->charcnt = 0;
+    sp->goback = sp->goahead = false;
+    init_ttinfo(&sp->ttis[0], 0, false, 0);
+    strcpy(sp->chars, utc);
+    sp->defaulttype = 0;
+    return 0;
+  } else {
+    int err = tzload(name, sp, true);
+    if (err != 0 && name && name[0] != ':' && tzparse(name, sp, NULL))
+      err = 0;
+    if (err == 0)
+      scrub_abbrs(sp);
+    return err;
+  }
+}
+
+static void
+tzset_unlocked(void)
+{
+  char const *name = getenv("TZ");
+  struct state *sp = lclptr;
+  int lcl = name ? strlen(name) < sizeof lcl_TZname : -1;
+  if (lcl < 0
+      ? lcl_is_set < 0
+      : 0 < lcl_is_set && strcmp(lcl_TZname, name) == 0)
+    if (recheck_tzdata() == 0)
+      return;
+#ifdef ALL_STATE
+  if (! sp)
+    lclptr = sp = malloc(sizeof *lclptr);
+#endif /* defined ALL_STATE */
+  if (sp) {
+    if (zoneinit(sp, name) != 0)
+      zoneinit(sp, "");
+    if (0 < lcl)
+      strcpy(lcl_TZname, name);
+  }
+  settzname();
+  lcl_is_set = lcl;
+}
+
+void
+tzset(void)
+{
+  if (lock() != 0)
+    return;
+  tzset_unlocked();
+  unlock();
+}
+
+static void
+gmtcheck(void)
+{
+  static bool gmt_is_set;
+  if (lock() != 0)
+    return;
+  if (! gmt_is_set) {
+#ifdef ALL_STATE
+    gmtptr = malloc(sizeof *gmtptr);
+#endif
+    if (gmtptr)
+      gmtload(gmtptr);
+    gmt_is_set = true;
+  }
+  unlock();
+}
+
+#if NETBSD_INSPIRED
+
+timezone_t
+tzalloc(char const *name)
+{
+  timezone_t sp = malloc(sizeof *sp);
+  if (sp) {
+    int err = zoneinit(sp, name);
+    if (err != 0) {
+      free(sp);
+      errno = err;
+      return NULL;
+    }
+  } else if (!HAVE_MALLOC_ERRNO)
+    errno = ENOMEM;
+  return sp;
+}
+
+void
+tzfree(timezone_t sp)
+{
+  free(sp);
+}
+
+/*
+** NetBSD 6.1.4 has ctime_rz, but omit it because POSIX says ctime and
+** ctime_r are obsolescent and have potential security problems that
+** ctime_rz would share.  Callers can instead use localtime_rz + strftime.
+**
+** NetBSD 6.1.4 has tzgetname, but omit it because it doesn't work
+** in zones with three or more time zone abbreviations.
+** Callers can instead use localtime_rz + strftime.
+*/
+
+#endif
+
+/*
+** The easy way to behave "as if no library function calls" localtime
+** is to not call it, so we drop its guts into "localsub", which can be
+** freely called. (And no, the PANS doesn't require the above behavior,
+** but it *is* desirable.)
+**
+** If successful and SETNAME is nonzero,
+** set the applicable parts of tzname, timezone and altzone;
+** however, it's OK to omit this step if the timezone is POSIX-compatible,
+** since in that case tzset should have already done this step correctly.
+** SETNAME's type is int_fast32_t for compatibility with gmtsub,
+** but it is actually a boolean and its value should be 0 or 1.
+*/
+
+/*ARGSUSED*/
+static struct tm *
+localsub(struct state const *sp, time_t const *timep, int_fast32_t setname,
+	 struct tm *const tmp)
+{
+	register const struct ttinfo *	ttisp;
+	register int			i;
+	register struct tm *		result;
+	const time_t			t = *timep;
+
+	if (sp == NULL) {
+	  /* Don't bother to set tzname etc.; tzset has already done it.  */
+	  return gmtsub(gmtptr, timep, 0, tmp);
+	}
+	if ((sp->goback && t < sp->ats[0]) ||
+		(sp->goahead && t > sp->ats[sp->timecnt - 1])) {
+			time_t newt;
+			register time_t		seconds;
+			register time_t		years;
+
+			if (t < sp->ats[0])
+				seconds = sp->ats[0] - t;
+			else	seconds = t - sp->ats[sp->timecnt - 1];
+			--seconds;
+
+			/* Beware integer overflow, as SECONDS might
+			   be close to the maximum time_t.  */
+			years = seconds / SECSPERREPEAT * YEARSPERREPEAT;
+			seconds = years * AVGSECSPERYEAR;
+			years += YEARSPERREPEAT;
+			if (t < sp->ats[0])
+			  newt = t + seconds + SECSPERREPEAT;
+			else
+			  newt = t - seconds - SECSPERREPEAT;
+
+			if (newt < sp->ats[0] ||
+				newt > sp->ats[sp->timecnt - 1])
+					return NULL;	/* "cannot happen" */
+			result = localsub(sp, &newt, setname, tmp);
+			if (result) {
+#if defined ckd_add && defined ckd_sub
+				if (t < sp->ats[0]
+				    ? ckd_sub(&result->tm_year,
+					      result->tm_year, years)
+				    : ckd_add(&result->tm_year,
+					      result->tm_year, years))
+				  return NULL;
+#else
+				register int_fast64_t newy;
+
+				newy = result->tm_year;
+				if (t < sp->ats[0])
+					newy -= years;
+				else	newy += years;
+				if (! (INT_MIN <= newy && newy <= INT_MAX))
+					return NULL;
+				result->tm_year = newy;
+#endif
+			}
+			return result;
+	}
+	if (sp->timecnt == 0 || t < sp->ats[0]) {
+		i = sp->defaulttype;
+	} else {
+		register int	lo = 1;
+		register int	hi = sp->timecnt;
+
+		while (lo < hi) {
+			register int	mid = (lo + hi) >> 1;
+
+			if (t < sp->ats[mid])
+				hi = mid;
+			else	lo = mid + 1;
+		}
+		i = sp->types[lo - 1];
+	}
+	ttisp = &sp->ttis[i];
+	/*
+	** To get (wrong) behavior that's compatible with System V Release 2.0
+	** you'd replace the statement below with
+	**	t += ttisp->tt_utoff;
+	**	timesub(&t, 0L, sp, tmp);
+	*/
+	result = timesub(&t, ttisp->tt_utoff, sp, tmp);
+	if (result) {
+	  result->tm_isdst = ttisp->tt_isdst;
+#ifdef TM_ZONE
+	  result->TM_ZONE = (char *) &sp->chars[ttisp->tt_desigidx];
+#endif /* defined TM_ZONE */
+	  if (setname)
+	    update_tzname_etc(sp, ttisp);
+	}
+	return result;
+}
+
+#if NETBSD_INSPIRED
+
+struct tm *
+localtime_rz(struct state *sp, time_t const *timep, struct tm *tmp)
+{
+  return localsub(sp, timep, 0, tmp);
+}
+
+#endif
+
+static struct tm *
+localtime_tzset(time_t const *timep, struct tm *tmp, bool setname)
+{
+  int err = lock();
+  if (err) {
+    errno = err;
+    return NULL;
+  }
+#ifndef DETECT_TZ_CHANGES
+  if (setname || !lcl_is_set)
+#endif
+    tzset_unlocked();
+  tmp = localsub(lclptr, timep, setname, tmp);
+  unlock();
+  return tmp;
+}
+
+static void
+localtime_key_init(void)
+{
+
+	localtime_key_error = _pthread_key_create(&localtime_key, free);
+}
+
+struct tm *
+localtime(const time_t *timep)
+{
+	struct tm *p_tm = &tm;
+
+	if (__isthreaded != 0) {
+		_pthread_once(&localtime_once, localtime_key_init);
+		if (localtime_key_error != 0) {
+			errno = localtime_key_error;
+			return (NULL);
+		}
+		if ((p_tm = _pthread_getspecific(localtime_key)) == NULL) {
+			if ((p_tm = malloc(sizeof(*p_tm))) == NULL) {
+				return (NULL);
+			}
+			_pthread_setspecific(localtime_key, p_tm);
+		}
+	}
+	return localtime_tzset(timep, p_tm, true);
+}
+
+struct tm *
+localtime_r(const time_t *timep, struct tm *tmp)
+{
+  return localtime_tzset(timep, tmp, false);
+}
+
+/*
+** gmtsub is to gmtime as localsub is to localtime.
+*/
+
+static struct tm *
+gmtsub(ATTRIBUTE_MAYBE_UNUSED struct state const *sp, time_t const *timep,
+       int_fast32_t offset, struct tm *tmp)
+{
+	register struct tm *	result;
+
+	result = timesub(timep, offset, gmtptr, tmp);
+#ifdef TM_ZONE
+	/*
+	** Could get fancy here and deliver something such as
+	** "+xx" or "-xx" if offset is non-zero,
+	** but this is no time for a treasure hunt.
+	*/
+	tmp->TM_ZONE = ((char *)
+			(offset ? wildabbr : gmtptr ? gmtptr->chars : utc));
+#endif /* defined TM_ZONE */
+	return result;
+}
+
+/*
+* Re-entrant version of gmtime.
+*/
+
+struct tm *
+gmtime_r(const time_t *timep, struct tm *tmp)
+{
+	_once(&gmt_once, gmtcheck);
+	return gmtsub(gmtptr, timep, 0, tmp);
+}
+
+static void
+gmtime_key_init(void)
+{
+
+	gmtime_key_error = _pthread_key_create(&gmtime_key, free);
+}
+
+struct tm *
+gmtime(const time_t *timep)
+{
+	struct tm *p_tm = &tm;
+
+	if (__isthreaded != 0) {
+		_pthread_once(&gmtime_once, gmtime_key_init);
+		if (gmtime_key_error != 0) {
+			errno = gmtime_key_error;
+			return (NULL);
+		}
+		if ((p_tm = _pthread_getspecific(gmtime_key)) == NULL) {
+			if ((p_tm = malloc(sizeof(*p_tm))) == NULL) {
+				return (NULL);
+			}
+			_pthread_setspecific(gmtime_key, p_tm);
+		}
+	}
+	return gmtime_r(timep, p_tm);
+}
+
+#ifdef STD_INSPIRED
+
+struct tm *
+offtime(const time_t *timep, long offset)
+{
+  _once(&gmt_once, gmtcheck);
+  return gmtsub(gmtptr, timep, offset, &tm);
+}
+
+#endif /* defined STD_INSPIRED */
+
+/*
+** Return the number of leap years through the end of the given year
+** where, to make the math easy, the answer for year zero is defined as zero.
+*/
+
+static time_t
+leaps_thru_end_of_nonneg(time_t y)
+{
+  return y / 4 - y / 100 + y / 400;
+}
+
+static time_t
+leaps_thru_end_of(time_t y)
+{
+  return (y < 0
+	  ? -1 - leaps_thru_end_of_nonneg(-1 - y)
+	  : leaps_thru_end_of_nonneg(y));
+}
+
+static struct tm *
+timesub(const time_t *timep, int_fast32_t offset,
+	const struct state *sp, struct tm *tmp)
+{
+	register const struct lsinfo *	lp;
+	register time_t			tdays;
+	register const int *		ip;
+	register int_fast32_t		corr;
+	register int			i;
+	int_fast32_t idays, rem, dayoff, dayrem;
+	time_t y;
+
+	/* If less than SECSPERMIN, the number of seconds since the
+	   most recent positive leap second; otherwise, do not add 1
+	   to localtime tm_sec because of leap seconds.  */
+	time_t secs_since_posleap = SECSPERMIN;
+
+	corr = 0;
+	i = (sp == NULL) ? 0 : sp->leapcnt;
+	while (--i >= 0) {
+		lp = &sp->lsis[i];
+		if (*timep >= lp->ls_trans) {
+			corr = lp->ls_corr;
+			if ((i == 0 ? 0 : lp[-1].ls_corr) < corr)
+			  secs_since_posleap = *timep - lp->ls_trans;
+			break;
+		}
+	}
+
+	/* Calculate the year, avoiding integer overflow even if
+	   time_t is unsigned.  */
+	tdays = *timep / SECSPERDAY;
+	rem = *timep % SECSPERDAY;
+	rem += offset % SECSPERDAY - corr % SECSPERDAY + 3 * SECSPERDAY;
+	dayoff = offset / SECSPERDAY - corr / SECSPERDAY + rem / SECSPERDAY - 3;
+	rem %= SECSPERDAY;
+	/* y = (EPOCH_YEAR
+	        + floor((tdays + dayoff) / DAYSPERREPEAT) * YEARSPERREPEAT),
+	   sans overflow.  But calculate against 1570 (EPOCH_YEAR -
+	   YEARSPERREPEAT) instead of against 1970 so that things work
+	   for localtime values before 1970 when time_t is unsigned.  */
+	dayrem = tdays % DAYSPERREPEAT;
+	dayrem += dayoff % DAYSPERREPEAT;
+	y = (EPOCH_YEAR - YEARSPERREPEAT
+	     + ((1 + dayoff / DAYSPERREPEAT + dayrem / DAYSPERREPEAT
+		 - ((dayrem % DAYSPERREPEAT) < 0)
+		 + tdays / DAYSPERREPEAT)
+		* YEARSPERREPEAT));
+	/* idays = (tdays + dayoff) mod DAYSPERREPEAT, sans overflow.  */
+	idays = tdays % DAYSPERREPEAT;
+	idays += dayoff % DAYSPERREPEAT + 2 * DAYSPERREPEAT;
+	idays %= DAYSPERREPEAT;
+	/* Increase Y and decrease IDAYS until IDAYS is in range for Y.  */
+	while (year_lengths[isleap(y)] <= idays) {
+		int tdelta = idays / DAYSPERLYEAR;
+		int_fast32_t ydelta = tdelta + !tdelta;
+		time_t newy = y + ydelta;
+		register int	leapdays;
+		leapdays = leaps_thru_end_of(newy - 1) -
+			leaps_thru_end_of(y - 1);
+		idays -= ydelta * DAYSPERNYEAR;
+		idays -= leapdays;
+		y = newy;
+	}
+
+#ifdef ckd_add
+	if (ckd_add(&tmp->tm_year, y, -TM_YEAR_BASE)) {
+	  errno = EOVERFLOW;
+	  return NULL;
+	}
+#else
+	if (!TYPE_SIGNED(time_t) && y < TM_YEAR_BASE) {
+	  int signed_y = y;
+	  tmp->tm_year = signed_y - TM_YEAR_BASE;
+	} else if ((!TYPE_SIGNED(time_t) || INT_MIN + TM_YEAR_BASE <= y)
+		   && y - TM_YEAR_BASE <= INT_MAX)
+	  tmp->tm_year = y - TM_YEAR_BASE;
+	else {
+	  errno = EOVERFLOW;
+	  return NULL;
+	}
+#endif
+	tmp->tm_yday = idays;
+	/*
+	** The "extra" mods below avoid overflow problems.
+	*/
+	tmp->tm_wday = (TM_WDAY_BASE
+			+ ((tmp->tm_year % DAYSPERWEEK)
+			   * (DAYSPERNYEAR % DAYSPERWEEK))
+			+ leaps_thru_end_of(y - 1)
+			- leaps_thru_end_of(TM_YEAR_BASE - 1)
+			+ idays);
+	tmp->tm_wday %= DAYSPERWEEK;
+	if (tmp->tm_wday < 0)
+		tmp->tm_wday += DAYSPERWEEK;
+	tmp->tm_hour = rem / SECSPERHOUR;
+	rem %= SECSPERHOUR;
+	tmp->tm_min = rem / SECSPERMIN;
+	tmp->tm_sec = rem % SECSPERMIN;
+
+	/* Use "... ??:??:60" at the end of the localtime minute containing
+	   the second just before the positive leap second.  */
+	tmp->tm_sec += secs_since_posleap <= tmp->tm_sec;
+
+	ip = mon_lengths[isleap(y)];
+	for (tmp->tm_mon = 0; idays >= ip[tmp->tm_mon]; ++(tmp->tm_mon))
+		idays -= ip[tmp->tm_mon];
+	tmp->tm_mday = idays + 1;
+	tmp->tm_isdst = 0;
+#ifdef TM_GMTOFF
+	tmp->TM_GMTOFF = offset;
+#endif /* defined TM_GMTOFF */
+	return tmp;
+}
+
+char *
+ctime(const time_t *timep)
+{
+/*
+** Section 4.12.3.2 of X3.159-1989 requires that
+**	The ctime function converts the calendar time pointed to by timer
+**	to local time in the form of a string. It is equivalent to
+**		asctime(localtime(timer))
+*/
+  struct tm *tmp = localtime(timep);
+  return tmp ? asctime(tmp) : NULL;
+}
+
+char *
+ctime_r(const time_t *timep, char *buf)
+{
+  struct tm mytm;
+  struct tm *tmp = localtime_r(timep, &mytm);
+  return tmp ? asctime_r(tmp, buf) : NULL;
+}
+
+/*
+** Adapted from code provided by Robert Elz, who writes:
+**	The "best" way to do mktime I think is based on an idea of Bob
+**	Kridle's (so its said...) from a long time ago.
+**	It does a binary search of the time_t space. Since time_t's are
+**	just 32 bits, its a max of 32 iterations (even at 64 bits it
+**	would still be very reasonable).
+*/
+
+#ifndef WRONG
+# define WRONG (-1)
+#endif /* !defined WRONG */
+
+/*
+** Normalize logic courtesy Paul Eggert.
+*/
+
+static bool
+increment_overflow(int *ip, int j)
+{
+#ifdef ckd_add
+	return ckd_add(ip, *ip, j);
+#else
+	register int const	i = *ip;
+
+	/*
+	** If i >= 0 there can only be overflow if i + j > INT_MAX
+	** or if j > INT_MAX - i; given i >= 0, INT_MAX - i cannot overflow.
+	** If i < 0 there can only be overflow if i + j < INT_MIN
+	** or if j < INT_MIN - i; given i < 0, INT_MIN - i cannot overflow.
+	*/
+	if ((i >= 0) ? (j > INT_MAX - i) : (j < INT_MIN - i))
+		return true;
+	*ip += j;
+	return false;
+#endif
+}
+
+static bool
+increment_overflow32(int_fast32_t *const lp, int const m)
+{
+#ifdef ckd_add
+	return ckd_add(lp, *lp, m);
+#else
+	register int_fast32_t const	l = *lp;
+
+	if ((l >= 0) ? (m > INT_FAST32_MAX - l) : (m < INT_FAST32_MIN - l))
+		return true;
+	*lp += m;
+	return false;
+#endif
+}
+
+static bool
+increment_overflow_time(time_t *tp, int_fast32_t j)
+{
+#ifdef ckd_add
+	return ckd_add(tp, *tp, j);
+#else
+	/*
+	** This is like
+	** 'if (! (TIME_T_MIN <= *tp + j && *tp + j <= TIME_T_MAX)) ...',
+	** except that it does the right thing even if *tp + j would overflow.
+	*/
+	if (! (j < 0
+	       ? (TYPE_SIGNED(time_t) ? TIME_T_MIN - j <= *tp : -1 - j < *tp)
+	       : *tp <= TIME_T_MAX - j))
+		return true;
+	*tp += j;
+	return false;
+#endif
+}
+
+static bool
+normalize_overflow(int *const tensptr, int *const unitsptr, const int base)
+{
+	register int	tensdelta;
+
+	tensdelta = (*unitsptr >= 0) ?
+		(*unitsptr / base) :
+		(-1 - (-1 - *unitsptr) / base);
+	*unitsptr -= tensdelta * base;
+	return increment_overflow(tensptr, tensdelta);
+}
+
+static bool
+normalize_overflow32(int_fast32_t *tensptr, int *unitsptr, int base)
+{
+	register int	tensdelta;
+
+	tensdelta = (*unitsptr >= 0) ?
+		(*unitsptr / base) :
+		(-1 - (-1 - *unitsptr) / base);
+	*unitsptr -= tensdelta * base;
+	return increment_overflow32(tensptr, tensdelta);
+}
+
+static int
+tmcomp(register const struct tm *const atmp,
+       register const struct tm *const btmp)
+{
+	register int	result;
+
+	if (atmp->tm_year != btmp->tm_year)
+		return atmp->tm_year < btmp->tm_year ? -1 : 1;
+	if ((result = (atmp->tm_mon - btmp->tm_mon)) == 0 &&
+		(result = (atmp->tm_mday - btmp->tm_mday)) == 0 &&
+		(result = (atmp->tm_hour - btmp->tm_hour)) == 0 &&
+		(result = (atmp->tm_min - btmp->tm_min)) == 0)
+			result = atmp->tm_sec - btmp->tm_sec;
+	return result;
+}
+
+/* Copy to *DEST from *SRC.  Copy only the members needed for mktime,
+   as other members might not be initialized.  */
+static void
+mktmcpy(struct tm *dest, struct tm const *src)
+{
+  dest->tm_sec = src->tm_sec;
+  dest->tm_min = src->tm_min;
+  dest->tm_hour = src->tm_hour;
+  dest->tm_mday = src->tm_mday;
+  dest->tm_mon = src->tm_mon;
+  dest->tm_year = src->tm_year;
+  dest->tm_isdst = src->tm_isdst;
+#if defined TM_GMTOFF && ! UNINIT_TRAP
+  dest->TM_GMTOFF = src->TM_GMTOFF;
+#endif
+}
+
+static time_t
+time2sub(struct tm *const tmp,
+	 struct tm *(*funcp)(struct state const *, time_t const *,
+			     int_fast32_t, struct tm *),
+	 struct state const *sp,
+	 const int_fast32_t offset,
+	 bool *okayp,
+	 bool do_norm_secs)
+{
+	register int			dir;
+	register int			i, j;
+	register int			saved_seconds;
+	register int_fast32_t		li;
+	register time_t			lo;
+	register time_t			hi;
+	int_fast32_t			y;
+	time_t				newt;
+	time_t				t;
+	struct tm			yourtm, mytm;
+
+	*okayp = false;
+	mktmcpy(&yourtm, tmp);
+
+	if (do_norm_secs) {
+		if (normalize_overflow(&yourtm.tm_min, &yourtm.tm_sec,
+			SECSPERMIN))
+				return WRONG;
+	}
+	if (normalize_overflow(&yourtm.tm_hour, &yourtm.tm_min, MINSPERHOUR))
+		return WRONG;
+	if (normalize_overflow(&yourtm.tm_mday, &yourtm.tm_hour, HOURSPERDAY))
+		return WRONG;
+	y = yourtm.tm_year;
+	if (normalize_overflow32(&y, &yourtm.tm_mon, MONSPERYEAR))
+		return WRONG;
+	/*
+	** Turn y into an actual year number for now.
+	** It is converted back to an offset from TM_YEAR_BASE later.
+	*/
+	if (increment_overflow32(&y, TM_YEAR_BASE))
+		return WRONG;
+	while (yourtm.tm_mday <= 0) {
+		if (increment_overflow32(&y, -1))
+			return WRONG;
+		li = y + (1 < yourtm.tm_mon);
+		yourtm.tm_mday += year_lengths[isleap(li)];
+	}
+	while (yourtm.tm_mday > DAYSPERLYEAR) {
+		li = y + (1 < yourtm.tm_mon);
+		yourtm.tm_mday -= year_lengths[isleap(li)];
+		if (increment_overflow32(&y, 1))
+			return WRONG;
+	}
+	for ( ; ; ) {
+		i = mon_lengths[isleap(y)][yourtm.tm_mon];
+		if (yourtm.tm_mday <= i)
+			break;
+		yourtm.tm_mday -= i;
+		if (++yourtm.tm_mon >= MONSPERYEAR) {
+			yourtm.tm_mon = 0;
+			if (increment_overflow32(&y, 1))
+				return WRONG;
+		}
+	}
+#ifdef ckd_add
+	if (ckd_add(&yourtm.tm_year, y, -TM_YEAR_BASE))
+	  return WRONG;
+#else
+	if (increment_overflow32(&y, -TM_YEAR_BASE))
+		return WRONG;
+	if (! (INT_MIN <= y && y <= INT_MAX))
+		return WRONG;
+	yourtm.tm_year = y;
+#endif
+	if (yourtm.tm_sec >= 0 && yourtm.tm_sec < SECSPERMIN)
+		saved_seconds = 0;
+	else if (yourtm.tm_year < EPOCH_YEAR - TM_YEAR_BASE) {
+		/*
+		** We can't set tm_sec to 0, because that might push the
+		** time below the minimum representable time.
+		** Set tm_sec to 59 instead.
+		** This assumes that the minimum representable time is
+		** not in the same minute that a leap second was deleted from,
+		** which is a safer assumption than using 58 would be.
+		*/
+		if (increment_overflow(&yourtm.tm_sec, 1 - SECSPERMIN))
+			return WRONG;
+		saved_seconds = yourtm.tm_sec;
+		yourtm.tm_sec = SECSPERMIN - 1;
+	} else {
+		saved_seconds = yourtm.tm_sec;
+		yourtm.tm_sec = 0;
+	}
+	/*
+	** Do a binary search (this works whatever time_t's type is).
+	*/
+	lo = TIME_T_MIN;
+	hi = TIME_T_MAX;
+	for ( ; ; ) {
+		t = lo / 2 + hi / 2;
+		if (t < lo)
+			t = lo;
+		else if (t > hi)
+			t = hi;
+		if (! funcp(sp, &t, offset, &mytm)) {
+			/*
+			** Assume that t is too extreme to be represented in
+			** a struct tm; arrange things so that it is less
+			** extreme on the next pass.
+			*/
+			dir = (t > 0) ? 1 : -1;
+		} else	dir = tmcomp(&mytm, &yourtm);
+		if (dir != 0) {
+			if (t == lo) {
+				if (t == TIME_T_MAX)
+					return WRONG;
+				++t;
+				++lo;
+			} else if (t == hi) {
+				if (t == TIME_T_MIN)
+					return WRONG;
+				--t;
+				--hi;
+			}
+			if (lo > hi)
+				return WRONG;
+			if (dir > 0)
+				hi = t;
+			else	lo = t;
+			continue;
+		}
+#if defined TM_GMTOFF && ! UNINIT_TRAP
+		if (mytm.TM_GMTOFF != yourtm.TM_GMTOFF
+		    && (yourtm.TM_GMTOFF < 0
+			? (-SECSPERDAY <= yourtm.TM_GMTOFF
+			   && (mytm.TM_GMTOFF <=
+			       (min(INT_FAST32_MAX, LONG_MAX)
+				+ yourtm.TM_GMTOFF)))
+			: (yourtm.TM_GMTOFF <= SECSPERDAY
+			   && ((max(INT_FAST32_MIN, LONG_MIN)
+				+ yourtm.TM_GMTOFF)
+			       <= mytm.TM_GMTOFF)))) {
+		  /* MYTM matches YOURTM except with the wrong UT offset.
+		     YOURTM.TM_GMTOFF is plausible, so try it instead.
+		     It's OK if YOURTM.TM_GMTOFF contains uninitialized data,
+		     since the guess gets checked.  */
+		  time_t altt = t;
+		  int_fast32_t diff = mytm.TM_GMTOFF - yourtm.TM_GMTOFF;
+		  if (!increment_overflow_time(&altt, diff)) {
+		    struct tm alttm;
+		    if (funcp(sp, &altt, offset, &alttm)
+			&& alttm.tm_isdst == mytm.tm_isdst
+			&& alttm.TM_GMTOFF == yourtm.TM_GMTOFF
+			&& tmcomp(&alttm, &yourtm) == 0) {
+		      t = altt;
+		      mytm = alttm;
+		    }
+		  }
+		}
+#endif
+		if (yourtm.tm_isdst < 0 || mytm.tm_isdst == yourtm.tm_isdst)
+			break;
+		/*
+		** Right time, wrong type.
+		** Hunt for right time, right type.
+		** It's okay to guess wrong since the guess
+		** gets checked.
+		*/
+		if (sp == NULL)
+			return WRONG;
+		for (i = sp->typecnt - 1; i >= 0; --i) {
+			if (sp->ttis[i].tt_isdst != yourtm.tm_isdst)
+				continue;
+			for (j = sp->typecnt - 1; j >= 0; --j) {
+				if (sp->ttis[j].tt_isdst == yourtm.tm_isdst)
+					continue;
+				if (ttunspecified(sp, j))
+				  continue;
+				newt = (t + sp->ttis[j].tt_utoff
+					- sp->ttis[i].tt_utoff);
+				if (! funcp(sp, &newt, offset, &mytm))
+					continue;
+				if (tmcomp(&mytm, &yourtm) != 0)
+					continue;
+				if (mytm.tm_isdst != yourtm.tm_isdst)
+					continue;
+				/*
+				** We have a match.
+				*/
+				t = newt;
+				goto label;
+			}
+		}
+		return WRONG;
+	}
+label:
+	newt = t + saved_seconds;
+	if ((newt < t) != (saved_seconds < 0))
+		return WRONG;
+	t = newt;
+	if (funcp(sp, &t, offset, tmp))
+		*okayp = true;
+	return t;
+}
+
+static time_t
+time2(struct tm * const	tmp,
+      struct tm *(*funcp)(struct state const *, time_t const *,
+			  int_fast32_t, struct tm *),
+      struct state const *sp,
+      const int_fast32_t offset,
+      bool *okayp)
+{
+	time_t	t;
+
+	/*
+	** First try without normalization of seconds
+	** (in case tm_sec contains a value associated with a leap second).
+	** If that fails, try with normalization of seconds.
+	*/
+	t = time2sub(tmp, funcp, sp, offset, okayp, false);
+	return *okayp ? t : time2sub(tmp, funcp, sp, offset, okayp, true);
+}
+
+static time_t
+time1(struct tm *const tmp,
+      struct tm *(*funcp)(struct state const *, time_t const *,
+			  int_fast32_t, struct tm *),
+      struct state const *sp,
+      const int_fast32_t offset)
+{
+	register time_t			t;
+	register int			samei, otheri;
+	register int			sameind, otherind;
+	register int			i;
+	register int			nseen;
+	char				seen[TZ_MAX_TYPES];
+	unsigned char			types[TZ_MAX_TYPES];
+	bool				okay;
+
+	if (tmp == NULL) {
+		errno = EINVAL;
+		return WRONG;
+	}
+
+	if (tmp->tm_isdst > 1)
+		tmp->tm_isdst = 1;
+	t = time2(tmp, funcp, sp, offset, &okay);
+	if (okay)
+		return t;
+	if (tmp->tm_isdst < 0)
+#ifdef PCTS
+		/*
+		** POSIX Conformance Test Suite code courtesy Grant Sullivan.
+		*/
+		tmp->tm_isdst = 0;	/* reset to std and try again */
+#else
+		return t;
+#endif /* !defined PCTS */
+	/*
+	** We're supposed to assume that somebody took a time of one type
+	** and did some math on it that yielded a "struct tm" that's bad.
+	** We try to divine the type they started from and adjust to the
+	** type they need.
+	*/
+	if (sp == NULL)
+		return WRONG;
+	for (i = 0; i < sp->typecnt; ++i)
+		seen[i] = false;
+	nseen = 0;
+	for (i = sp->timecnt - 1; i >= 0; --i)
+		if (!seen[sp->types[i]] && !ttunspecified(sp, sp->types[i])) {
+			seen[sp->types[i]] = true;
+			types[nseen++] = sp->types[i];
+		}
+	for (sameind = 0; sameind < nseen; ++sameind) {
+		samei = types[sameind];
+		if (sp->ttis[samei].tt_isdst != tmp->tm_isdst)
+			continue;
+		for (otherind = 0; otherind < nseen; ++otherind) {
+			otheri = types[otherind];
+			if (sp->ttis[otheri].tt_isdst == tmp->tm_isdst)
+				continue;
+			tmp->tm_sec += (sp->ttis[otheri].tt_utoff
+					- sp->ttis[samei].tt_utoff);
+			tmp->tm_isdst = !tmp->tm_isdst;
+			t = time2(tmp, funcp, sp, offset, &okay);
+			if (okay)
+				return t;
+			tmp->tm_sec -= (sp->ttis[otheri].tt_utoff
+					- sp->ttis[samei].tt_utoff);
+			tmp->tm_isdst = !tmp->tm_isdst;
+		}
+	}
+	return WRONG;
+}
+
+static time_t
+mktime_tzname(struct state *sp, struct tm *tmp, bool setname)
+{
+  if (sp)
+    return time1(tmp, localsub, sp, setname);
+  else {
+    _once(&gmt_once, gmtcheck);
+    return time1(tmp, gmtsub, gmtptr, 0);
+  }
+}
+
+#if NETBSD_INSPIRED
+
+time_t
+mktime_z(struct state *sp, struct tm *tmp)
+{
+  return mktime_tzname(sp, tmp, false);
+}
+
+#endif
+
+time_t
+mktime(struct tm *tmp)
+{
+  time_t t;
+  int err = lock();
+  if (err) {
+    errno = err;
+    return -1;
+  }
+  tzset_unlocked();
+  t = mktime_tzname(lclptr, tmp, true);
+  unlock();
+  return t;
+}
+
+#ifdef STD_INSPIRED
+time_t
+timelocal(struct tm *tmp)
+{
+	if (tmp != NULL)
+		tmp->tm_isdst = -1;	/* in case it wasn't initialized */
+	return mktime(tmp);
+}
+#else
+static
+#endif
+time_t
+timeoff(struct tm *tmp, long offset)
+{
+  if (tmp)
+    tmp->tm_isdst = 0;
+  _once(&gmt_once, gmtcheck);
+  return time1(tmp, gmtsub, gmtptr, offset);
+}
+
+time_t
+timegm(struct tm *tmp)
+{
+  time_t t;
+  struct tm tmcpy;
+  mktmcpy(&tmcpy, tmp);
+  tmcpy.tm_wday = -1;
+  t = timeoff(&tmcpy, 0);
+  if (0 <= tmcpy.tm_wday)
+    *tmp = tmcpy;
+  return t;
+}
+
+static int_fast32_t
+leapcorr(struct state const *sp, time_t t)
+{
+	register struct lsinfo const *	lp;
+	register int			i;
+
+	i = sp->leapcnt;
+	while (--i >= 0) {
+		lp = &sp->lsis[i];
+		if (t >= lp->ls_trans)
+			return lp->ls_corr;
+	}
+	return 0;
+}
+
+/*
+** XXX--is the below the right way to conditionalize??
+*/
+
+#ifdef STD_INSPIRED
+
+/* NETBSD_INSPIRED_EXTERN functions are exported to callers if
+   NETBSD_INSPIRED is defined, and are private otherwise.  */
+# if NETBSD_INSPIRED
+#  define NETBSD_INSPIRED_EXTERN
+# else
+#  define NETBSD_INSPIRED_EXTERN static
+# endif
+
+/*
+** IEEE Std 1003.1 (POSIX) says that 536457599
+** shall correspond to "Wed Dec 31 23:59:59 UTC 1986", which
+** is not the case if we are accounting for leap seconds.
+** So, we provide the following conversion routines for use
+** when exchanging timestamps with POSIX conforming systems.
+*/
+
+NETBSD_INSPIRED_EXTERN time_t
+time2posix_z(struct state *sp, time_t t)
+{
+  return t - leapcorr(sp, t);
+}
+
+time_t
+time2posix(time_t t)
+{
+  int err = lock();
+  if (err) {
+    errno = err;
+    return -1;
+  }
+#ifndef DETECT_TZ_CHANGES
+  if (!lcl_is_set)
+#endif
+    tzset_unlocked();
+  if (lclptr)
+    t = time2posix_z(lclptr, t);
+  unlock();
+  return t;
+}
+
+NETBSD_INSPIRED_EXTERN time_t
+posix2time_z(struct state *sp, time_t t)
+{
+	time_t	x;
+	time_t	y;
+	/*
+	** For a positive leap second hit, the result
+	** is not unique. For a negative leap second
+	** hit, the corresponding time doesn't exist,
+	** so we return an adjacent second.
+	*/
+	x = t + leapcorr(sp, t);
+	y = x - leapcorr(sp, x);
+	if (y < t) {
+		do {
+			x++;
+			y = x - leapcorr(sp, x);
+		} while (y < t);
+		x -= y != t;
+	} else if (y > t) {
+		do {
+			--x;
+			y = x - leapcorr(sp, x);
+		} while (y > t);
+		x += y != t;
+	}
+	return x;
+}
+
+time_t
+posix2time(time_t t)
+{
+  int err = lock();
+  if (err) {
+    errno = err;
+    return -1;
+  }
+#ifndef DETECT_TZ_CHANGES
+  if (!lcl_is_set)
+#endif
+    tzset_unlocked();
+  if (lclptr)
+    t = posix2time_z(lclptr, t);
+  unlock();
+  return t;
+}
+
+#endif /* defined STD_INSPIRED */
+
+#if TZ_TIME_T
+
+# if !USG_COMPAT
+#  define daylight 0
+#  define timezone 0
+# endif
+# if !ALTZONE
+#  define altzone 0
+# endif
+
+/* Convert from the underlying system's time_t to the ersatz time_tz,
+   which is called 'time_t' in this file.  Typically, this merely
+   converts the time's integer width.  On some platforms, the system
+   time is local time not UT, or uses some epoch other than the POSIX
+   epoch.
+
+   Although this code appears to define a function named 'time' that
+   returns time_t, the macros in private.h cause this code to actually
+   define a function named 'tz_time' that returns tz_time_t.  The call
+   to sys_time invokes the underlying system's 'time' function.  */
+
+time_t
+time(time_t *p)
+{
+  time_t r = sys_time(0);
+  if (r != (time_t) -1) {
+    int_fast32_t offset = EPOCH_LOCAL ? (daylight ? timezone : altzone) : 0;
+    if (increment_overflow32(&offset, -EPOCH_OFFSET)
+	|| increment_overflow_time(&r, offset)) {
+      errno = EOVERFLOW;
+      r = -1;
+    }
+  }
+  if (p)
+    *p = r;
+  return r;
+}
+
+#endif
diff --git a/contrib/tzcode/newctime.3 b/contrib/tzcode/newctime.3
new file mode 100644
index 000000000000..e25d841ef537
--- /dev/null
+++ b/contrib/tzcode/newctime.3
@@ -0,0 +1,344 @@
+.\" This file is in the public domain, so clarified as of
+.\" 2009-05-17 by Arthur David Olson.
+.TH NEWCTIME 3
+.SH NAME
+asctime, ctime, difftime, gmtime, localtime, mktime \- convert date and time
+.SH SYNOPSIS
+.nf
+.ie \n(.g .ds - \f(CR-\fP
+.el .ds - \-
+.B #include <time.h>
+.PP
+.BR "extern char *tzname[];" " /\(** (optional) \(**/"
+.PP
+.B char *ctime(time_t const *clock);
+.PP
+.B char *ctime_r(time_t const *clock, char *buf);
+.PP
+.B double difftime(time_t time1, time_t time0);
+.PP
+.B char *asctime(struct tm const *tm);
+.PP
+.B "char *asctime_r(struct tm const *restrict tm,"
+.B "    char *restrict result);"
+.PP
+.B struct tm *localtime(time_t const *clock);
+.PP
+.B "struct tm *localtime_r(time_t const *restrict clock,"
+.B "    struct tm *restrict result);"
+.PP
+.B "struct tm *localtime_rz(timezone_t restrict zone,"
+.B "    time_t const *restrict clock,"
+.B "    struct tm *restrict result);"
+.PP
+.B struct tm *gmtime(time_t const *clock);
+.PP
+.B "struct tm *gmtime_r(time_t const *restrict clock,"
+.B "    struct tm *restrict result);"
+.PP
+.B time_t mktime(struct tm *tm);
+.PP
+.B "time_t mktime_z(timezone_t restrict zone,"
+.B "    struct tm *restrict tm);"
+.PP
+.B cc ... \*-ltz
+.fi
+.SH DESCRIPTION
+.ie '\(en'' .ds en \-
+.el .ds en \(en
+.ie '\(lq'' .ds lq \&"\"
+.el .ds lq \(lq\"
+.ie '\(rq'' .ds rq \&"\"
+.el .ds rq \(rq\"
+.de q
+\\$3\*(lq\\$1\*(rq\\$2
+..
+The
+.B ctime
+function
+converts a long integer, pointed to by
+.IR clock ,
+and returns a pointer to a
+string of the form
+.br
+.ce
+.eo
+Thu Nov 24 18:22:48 1986\n\0
+.br
+.ec
+Years requiring fewer than four characters are padded with leading zeroes.
+For years longer than four characters, the string is of the form
+.br
+.ce
+.eo
+Thu Nov 24 18:22:48     81986\n\0
+.ec
+.br
+with five spaces before the year.
+These unusual formats are designed to make it less likely that older
+software that expects exactly 26 bytes of output will mistakenly output
+misleading values for out-of-range years.
+.PP
+The
+.BI * clock
+timestamp represents the time in seconds since 1970-01-01 00:00:00
+Coordinated Universal Time (UTC).
+The POSIX standard says that timestamps must be nonnegative
+and must ignore leap seconds.
+Many implementations extend POSIX by allowing negative timestamps,
+and can therefore represent timestamps that predate the
+introduction of UTC and are some other flavor of Universal Time (UT).
+Some implementations support leap seconds, in contradiction to POSIX.
+.PP
+The
+.B localtime
+and
+.B gmtime
+functions
+return pointers to
+.q "tm"
+structures, described below.
+The
+.B localtime
+function
+corrects for the time zone and any time zone adjustments
+(such as Daylight Saving Time in the United States).
+After filling in the
+.q "tm"
+structure,
+.B localtime
+sets the
+.BR tm_isdst 'th
+element of
+.B tzname
+to a pointer to a string that's the time zone abbreviation to be used with
+.BR localtime 's
+return value.
+.PP
+The
+.B gmtime
+function
+converts to Coordinated Universal Time.
+.PP
+The
+.B asctime
+function
+converts a time value contained in a
+.q "tm"
+structure to a string,
+as shown in the above example,
+and returns a pointer to the string.
+.PP
+The
+.B mktime
+function
+converts the broken-down time,
+expressed as local time,
+in the structure pointed to by
+.I tm
+into a calendar time value with the same encoding as that of the values
+returned by the
+.B time
+function.
+The original values of the
+.B tm_wday
+and
+.B tm_yday
+components of the structure are ignored,
+and the original values of the other components are not restricted
+to their normal ranges.
+(A positive or zero value for
+.B tm_isdst
+causes
+.B mktime
+to presume initially that daylight saving time
+respectively,
+is or is not in effect for the specified time.
+A negative value for
+.B tm_isdst
+causes the
+.B mktime
+function to attempt to divine whether daylight saving time is in effect
+for the specified time; in this case it does not use a consistent
+rule and may give a different answer when later
+presented with the same argument.)
+On successful completion, the values of the
+.B tm_wday
+and
+.B tm_yday
+components of the structure are set appropriately,
+and the other components are set to represent the specified calendar time,
+but with their values forced to their normal ranges; the final value of
+.B tm_mday
+is not set until
+.B tm_mon
+and
+.B tm_year
+are determined.
+The
+.B mktime
+function
+returns the specified calendar time;
+If the calendar time cannot be represented,
+it returns \-1.
+.PP
+The
+.B difftime
+function
+returns the difference between two calendar times,
+.RI ( time1
+\-
+.IR time0 ),
+expressed in seconds.
+.PP
+The
+.BR ctime_r ,
+.BR localtime_r ,
+.BR gmtime_r ,
+and
+.B asctime_r
+functions
+are like their unsuffixed counterparts, except that they accept an
+additional argument specifying where to store the result if successful.
+.PP
+The
+.B localtime_rz
+and
+.B mktime_z
+functions
+are like their unsuffixed counterparts, except that they accept an
+extra initial
+.B zone
+argument specifying the timezone to be used for conversion.
+If
+.B zone
+is null, UT is used; otherwise,
+.B zone
+should be have been allocated by
+.B tzalloc
+and should not be freed until after all uses (e.g., by calls to
+.BR strftime )
+of the filled-in
+.B tm_zone
+fields.
+.PP
+Declarations of all the functions and externals, and the
+.q "tm"
+structure,
+are in the
+.B <time.h>
+header file.
+The structure (of type)
+.B struct tm
+includes the following fields:
+.RS
+.PP
+.nf
+.ta 2n +\w'long tm_gmtoff;nn'u
+	int tm_sec;	/\(** seconds (0\*(en60) \(**/
+	int tm_min;	/\(** minutes (0\*(en59) \(**/
+	int tm_hour;	/\(** hours (0\*(en23) \(**/
+	int tm_mday;	/\(** day of month (1\*(en31) \(**/
+	int tm_mon;	/\(** month of year (0\*(en11) \(**/
+	int tm_year;	/\(** year \- 1900 \(**/
+	int tm_wday;	/\(** day of week (Sunday = 0) \(**/
+	int tm_yday;	/\(** day of year (0\*(en365) \(**/
+	int tm_isdst;	/\(** is daylight saving time in effect? \(**/
+	char \(**tm_zone;	/\(** time zone abbreviation (optional) \(**/
+	long tm_gmtoff;	/\(** offset from UT in seconds (optional) \(**/
+.fi
+.RE
+.PP
+The
+.B tm_isdst
+field
+is non-zero if daylight saving time is in effect.
+.PP
+The
+.B tm_gmtoff
+field
+is the offset (in seconds) of the time represented
+from UT, with positive values indicating east
+of the Prime Meridian.
+The field's name is derived from Greenwich Mean Time, a precursor of UT.
+.PP
+In
+.B "struct tm"
+the
+.B tm_zone
+and
+.B tm_gmtoff
+fields exist, and are filled in, only if arrangements to do
+so were made when the library containing these functions was
+created.
+Similarly, the
+.B tzname
+variable is optional; also, there is no guarantee that
+.B tzname
+will
+continue to exist in this form in future releases of this code.
+.SH FILES
+.ta \w'/usr/share/zoneinfo/posixrules\0\0'u
+/usr/share/zoneinfo	timezone information directory
+.br
+/usr/share/zoneinfo/localtime	local timezone file
+.br
+/usr/share/zoneinfo/posixrules	used with POSIX-style TZ's
+.br
+/usr/share/zoneinfo/GMT	for UTC leap seconds
+.sp
+If
+.B /usr/share/zoneinfo/GMT
+is absent,
+UTC leap seconds are loaded from
+.BR /usr/share/zoneinfo/posixrules .
+.SH SEE ALSO
+getenv(3),
+newstrftime(3),
+newtzset(3),
+time(2),
+tzfile(5)
+.SH NOTES
+The return values of
+.BR asctime ,
+.BR ctime ,
+.BR gmtime ,
+and
+.B localtime
+point to static data
+overwritten by each call.
+The
+.B tzname
+variable (once set) and the
+.B tm_zone
+field of a returned
+.B "struct tm"
+both point to an array of characters that
+can be freed or overwritten by later calls to the functions
+.BR localtime ,
+.BR tzfree ,
+and
+.BR tzset ,
+if these functions affect the timezone information that specifies the
+abbreviation in question.
+The remaining functions and data are thread-safe.
+.PP
+The
+.BR asctime ,
+.BR asctime_r ,
+.BR ctime ,
+and
+.B ctime_r
+functions
+behave strangely for years before 1000 or after 9999.
+The 1989 and 1999 editions of the C Standard say
+that years from \-99 through 999 are converted without
+extra spaces, but this conflicts with longstanding
+tradition and with this implementation.
+The 2011 edition says that the behavior
+is undefined if the year is before 1000 or after 9999.
+Traditional implementations of these two functions are
+restricted to years in the range 1900 through 2099.
+To avoid this portability mess, new programs should use
+.B strftime
+instead.
diff --git a/contrib/tzcode/newstrftime.3 b/contrib/tzcode/newstrftime.3
new file mode 100644
index 000000000000..d5d8ee104d9f
--- /dev/null
+++ b/contrib/tzcode/newstrftime.3
@@ -0,0 +1,290 @@
+.\" strftime man page
+.\"
+.\" Based on the UCB file whose corrected copyright information appears below.
+.\" Copyright 1989, 1991 The Regents of the University of California.
+.\" All rights reserved.
+.\"
+.\" This code is derived from software contributed to Berkeley by
+.\" the American National Standards Committee X3, on Information
+.\" Processing Systems.
+.\"
+.\" Redistribution and use in source and binary forms, with or without
+.\" modification, are permitted provided that the following conditions
+.\" are met:
+.\" 1. Redistributions of source code must retain the above copyright
+.\"    notice, this list of conditions and the following disclaimer.
+.\" 2. Redistributions in binary form must reproduce the above copyright
+.\"    notice, this list of conditions and the following disclaimer in the
+.\"    documentation and/or other materials provided with the distribution.
+.\" 3. Neither the name of the University nor the names of its contributors
+.\"    may be used to endorse or promote products derived from this software
+.\"    without specific prior written permission.
+.\"
+.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS "AS IS" AND
+.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+.\" SUCH DAMAGE.
+.\"
+.\"     from: @(#)strftime.3	5.12 (Berkeley) 6/29/91
+.\"	$Id: strftime.3,v 1.4 1993/12/15 20:33:00 jtc Exp $
+.\"
+.TH NEWSTRFTIME 3
+.SH NAME
+strftime \- format date and time
+.SH SYNOPSIS
+.nf
+.ie \n(.g .ds - \f(CR-\fP
+.el .ds - \-
+.B #include <time.h>
+.PP
+.B "size_t strftime(char *restrict buf, size_t maxsize,"
+.B "    char const *restrict format, struct tm const *restrict timeptr);"
+.PP
+.B cc ... \-ltz
+.fi
+.SH DESCRIPTION
+.ie '\(lq'' .ds lq \&"\"
+.el .ds lq \(lq\"
+.ie '\(rq'' .ds rq \&"\"
+.el .ds rq \(rq\"
+.de c
+.ie \n(.g \f(CR\\$1\fP\\$2
+.el \\$1\\$2
+..
+.de q
+\\$3\*(lq\\$1\*(rq\\$2
+..
+The
+.B strftime
+function formats the information from
+.I timeptr
+into the array pointed to by
+.I buf
+according to the string pointed to by
+.IR format .
+.PP
+The
+.I format
+string consists of zero or more conversion specifications and
+ordinary characters.
+All ordinary characters are copied directly into the array.
+A conversion specification consists of a percent sign
+.Ql %
+and one other character.
+.PP
+No more than
+.I maxsize
+bytes are placed into the array.
+.PP
+Each conversion specification is replaced by the characters as
+follows which are then copied into the array.
+.TP
+%A
+is replaced by the locale's full weekday name.
+.TP
+%a
+is replaced by the locale's abbreviated weekday name.
+.TP
+%B
+is replaced by the locale's full month name.
+.TP
+%b or %h
+is replaced by the locale's abbreviated month name.
+.TP
+%C
+is replaced by the century (a year divided by 100 and truncated to an integer)
+as a decimal number [00,99].
+.TP
+%c
+is replaced by the locale's appropriate date and time representation.
+.TP
+%D
+is equivalent to
+.c %m/%d/%y .
+.TP
+%d
+is replaced by the day of the month as a decimal number [01,31].
+.TP
+%e
+is replaced by the day of month as a decimal number [1,31];
+single digits are preceded by a blank.
+.TP
+%F
+is equivalent to
+.c %Y-%m-%d
+(the ISO 8601 date format).
+.TP
+%G
+is replaced by the ISO 8601 year with century as a decimal number.
+See also the
+.c %V
+conversion specification.
+.TP
+%g
+is replaced by the ISO 8601 year without century as a decimal number [00,99].
+This is the year that includes the greater part of the week.
+(Monday as the first day of a week).
+See also the
+.c %V
+conversion specification.
+.TP
+%H
+is replaced by the hour (24-hour clock) as a decimal number [00,23].
+.TP
+%I
+is replaced by the hour (12-hour clock) as a decimal number [01,12].
+.TP
+%j
+is replaced by the day of the year as a decimal number [001,366].
+.TP
+%k
+is replaced by the hour (24-hour clock) as a decimal number [0,23];
+single digits are preceded by a blank.
+.TP
+%l
+is replaced by the hour (12-hour clock) as a decimal number [1,12];
+single digits are preceded by a blank.
+.TP
+%M
+is replaced by the minute as a decimal number [00,59].
+.TP
+%m
+is replaced by the month as a decimal number [01,12].
+.TP
+%n
+is replaced by a newline.
+.TP
+%p
+is replaced by the locale's equivalent of either
+.q AM
+or
+.q PM .
+.TP
+%R
+is replaced by the time in the format
+.c %H:%M .
+.TP
+%r
+is replaced by the locale's representation of 12-hour clock time
+using AM/PM notation.
+.TP
+%S
+is replaced by the second as a decimal number [00,60].
+The range of
+seconds is [00,60] instead of [00,59] to allow for the periodic occurrence
+of leap seconds.
+.TP
+%s
+is replaced by the number of seconds since the Epoch (see
+.BR ctime (3)).
+.TP
+%T
+is replaced by the time in the format
+.c %H:%M:%S .
+.TP
+%t
+is replaced by a tab.
+.TP
+%U
+is replaced by the week number of the year (Sunday as the first day of
+the week) as a decimal number [00,53].
+.TP
+%u
+is replaced by the weekday (Monday as the first day of the week)
+as a decimal number [1,7].
+.TP
+%V
+is replaced by the week number of the year (Monday as the first day of
+the week) as a decimal number [01,53].  If the week containing January
+1 has four or more days in the new year, then it is week 1; otherwise
+it is week 53 of the previous year, and the next week is week 1.
+The year is given by the
+.c %G
+conversion specification.
+.TP
+%W
+is replaced by the week number of the year (Monday as the first day of
+the week) as a decimal number [00,53].
+.TP
+%w
+is replaced by the weekday (Sunday as the first day of the week)
+as a decimal number [0,6].
+.TP
+%X
+is replaced by the locale's appropriate time representation.
+.TP
+%x
+is replaced by the locale's appropriate date representation.
+.TP
+%Y
+is replaced by the year with century as a decimal number.
+.TP
+%y
+is replaced by the year without century as a decimal number [00,99].
+.TP
+%Z
+is replaced by the time zone abbreviation,
+or by the empty string if this is not determinable.
+.TP
+%z
+is replaced by the offset from the Prime Meridian
+in the format +HHMM or \*-HHMM (ISO 8601) as appropriate,
+with positive values representing locations east of Greenwich,
+or by the empty string if this is not determinable.
+The numeric time zone abbreviation \*-0000 is used when the time is
+Universal Time
+but local time is indeterminate; by convention this is used for
+locations while uninhabited, and corresponds to a zero offset when the
+time zone abbreviation begins with
+.q "\*-" .
+.TP
+%%
+is replaced by a single %.
+.TP
+%+
+is replaced by the locale's date and time in
+.BR date (1)
+format.
+.SH "RETURN VALUE"
+If the conversion is successful,
+.B strftime
+returns the number of bytes placed into the array, not counting the
+terminating NUL;
+.B errno
+is unchanged if the returned value is zero.
+Otherwise,
+.B errno
+is set to indicate the error, zero is returned,
+and the array contents are unspecified.
+.SH ERRORS
+This function fails if:
+.TP
+[ERANGE]
+The total number of resulting bytes, including the terminating
+NUL character, is more than
+.IR maxsize .
+.PP
+This function may fail if:
+.TP
+[EOVERFLOW]
+The format includes an
+.c %s
+conversion and the number of seconds since the Epoch cannot be represented
+in a
+.c time_t .
+.SH SEE ALSO
+date(1),
+getenv(3),
+newctime(3),
+newtzset(3),
+time(2),
+tzfile(5)
+.SH BUGS
+There is no conversion specification for the phase of the moon.
diff --git a/contrib/tzcode/newtzset.3 b/contrib/tzcode/newtzset.3
new file mode 100644
index 000000000000..1e75acf0e6e3
--- /dev/null
+++ b/contrib/tzcode/newtzset.3
@@ -0,0 +1,350 @@
+.\" This file is in the public domain, so clarified as of
+.\" 2009-05-17 by Arthur David Olson.
+.TH NEWTZSET 3
+.SH NAME
+tzset \- initialize time conversion information
+.SH SYNOPSIS
+.nf
+.ie \n(.g .ds - \f(CR-\fP
+.el .ds - \-
+.B #include <time.h>
+.PP
+.B timezone_t tzalloc(char const *TZ);
+.PP
+.B void tzfree(timezone_t tz);
+.PP
+.B void tzset(void);
+.PP
+.B cc ... \*-ltz
+.fi
+.SH DESCRIPTION
+.ie '\(en'' .ds en \-
+.el .ds en \(en
+.ie '\(lq'' .ds lq \&"\"
+.el .ds lq \(lq\"
+.ie '\(rq'' .ds rq \&"\"
+.el .ds rq \(rq\"
+.de q
+\\$3\*(lq\\$1\*(rq\\$2
+..
+The
+.B tzalloc
+function
+allocates and returns a timezone object described by
+.BR TZ .
+If
+.B TZ
+is not a valid timezone description, or if the object cannot be allocated,
+.B tzalloc
+returns a null pointer and sets
+.BR errno .
+.PP
+The
+.B tzfree
+function
+frees a timezone object
+.BR tz ,
+which should have been successfully allocated by
+.BR tzalloc .
+This invalidates any
+.B tm_zone
+pointers that
+.B tz
+was used to set.
+.PP
+The
+.B tzset
+function
+acts like
+.BR tzalloc(getenv("TZ")) ,
+except it saves any resulting timezone object into internal
+storage that is accessed by
+.BR localtime ,
+.BR localtime_r ,
+and
+.BR mktime .
+The anonymous shared timezone object is freed by the next call to
+.BR tzset .
+If the implied call to
+.B tzalloc
+fails,
+.B tzset
+falls back on Universal Time (UT).
+.PP
+If
+.B TZ
+is null, the best available approximation to local (wall
+clock) time, as specified by the
+.BR tzfile (5)-format
+file
+.B localtime
+in the system time conversion information directory, is used.
+If
+.B TZ
+is the empty string,
+UT is used, with the abbreviation "UTC"
+and without leap second correction; please see
+.BR newctime (3)
+for more about UT, UTC, and leap seconds.  If
+.B TZ
+is nonnull and nonempty:
+.IP
+if the value begins with a colon, it is used as a pathname of a file
+from which to read the time conversion information;
+.IP
+if the value does not begin with a colon, it is first used as the
+pathname of a file from which to read the time conversion information,
+and, if that file cannot be read, is used directly as a specification of
+the time conversion information.
+.PP
+When
+.B TZ
+is used as a pathname, if it begins with a slash,
+it is used as an absolute pathname; otherwise,
+it is used as a pathname relative to a system time conversion information
+directory.
+The file must be in the format specified in
+.BR tzfile (5).
+.PP
+When
+.B TZ
+is used directly as a specification of the time conversion information,
+it must have the following syntax (spaces inserted for clarity):
+.IP
+\fIstd\|offset\fR[\fIdst\fR[\fIoffset\fR][\fB,\fIrule\fR]]
+.PP
+Where:
+.RS
+.TP 15
+.IR std " and " dst
+Three or more bytes that are the designation for the standard
+.RI ( std )
+or the alternative
+.RI ( dst ,
+such as daylight saving time)
+time zone.  Only
+.I std
+is required; if
+.I dst
+is missing, then daylight saving time does not apply in this locale.
+Upper- and lowercase letters are explicitly allowed.  Any characters
+except a leading colon
+.RB ( : ),
+digits, comma
+.RB ( , ),
+ASCII minus
+.RB ( \*- ),
+ASCII plus
+.RB ( + ),
+and NUL bytes are allowed.
+Alternatively, a designation can be surrounded by angle brackets
+.B <
+and
+.BR > ;
+in this case, the designation can contain any characters other than
+.B >
+and NUL.
+.TP
+.I offset
+Indicates the value one must add to the local time to arrive at
+Coordinated Universal Time.  The
+.I offset
+has the form:
+.RS
+.IP
+\fIhh\fR[\fB:\fImm\fR[\fB:\fIss\fR]]
+.RE
+.IP
+The minutes
+.RI ( mm )
+and seconds
+.RI ( ss )
+are optional.  The hour
+.RI ( hh )
+is required and may be a single digit.  The
+.I offset
+following
+.I std
+is required.  If no
+.I offset
+follows
+.IR dst ,
+daylight saving time is assumed to be one hour ahead of standard time.  One or
+more digits may be used; the value is always interpreted as a decimal
+number.  The hour must be between zero and 24, and the minutes (and
+seconds) \*(en if present \*(en between zero and 59.  If preceded by a
+.q "\*-" ,
+the time zone shall be east of the Prime Meridian; otherwise it shall be
+west (which may be indicated by an optional preceding
+.q "+" .
+.TP
+.I rule
+Indicates when to change to and back from daylight saving time.  The
+.I rule
+has the form:
+.RS
+.IP
+\fIdate\fB/\fItime\fB,\fIdate\fB/\fItime\fR
+.RE
+.IP
+where the first
+.I date
+describes when the change from standard to daylight saving time occurs and the
+second
+.I date
+describes when the change back happens.  Each
+.I time
+field describes when, in current local time, the change to the other
+time is made.
+As an extension to POSIX, daylight saving is assumed to be in effect
+all year if it begins January 1 at 00:00 and ends December 31 at
+24:00 plus the difference between daylight saving and standard time,
+leaving no room for standard time in the calendar.
+.IP
+The format of
+.I date
+is one of the following:
+.RS
+.TP 10
+.BI J n
+The Julian day
+.I n
+.RI "(1\ \(<=" "\ n\ " "\(<=\ 365).
+Leap days are not counted; that is, in all years \*(en including leap
+years \*(en February 28 is day 59 and March 1 is day 60.  It is
+impossible to explicitly refer to the occasional February 29.
+.TP
+.I n
+The zero-based Julian day
+.RI "(0\ \(<=" "\ n\ " "\(<=\ 365).
+Leap days are counted, and it is possible to refer to February 29.
+.TP
+.BI M m . n . d
+The
+.IR d' th
+day
+.RI "(0\ \(<=" "\ d\ " "\(<=\ 6)
+of week
+.I n
+of month
+.I m
+of the year
+.RI "(1\ \(<=" "\ n\ " "\(<=\ 5,
+.RI "1\ \(<=" "\ m\ " "\(<=\ 12,
+where week 5 means
+.q "the last \fId\fP day in month \fIm\fP"
+which may occur in either the fourth or the fifth week).  Week 1 is the
+first week in which the
+.IR d' th
+day occurs.  Day zero is Sunday.
+.RE
+.IP "" 15
+The
+.I time
+has the same format as
+.I offset
+except that POSIX does not allow a leading sign (\c
+.q "\*-"
+or
+.q "+" ).
+As an extension to POSIX, the hours part of
+.I time
+can range from \-167 through 167; this allows for unusual rules such
+as
+.q "the Saturday before the first Sunday of March" .
+The default, if
+.I time
+is not given, is
+.BR 02:00:00 .
+.RE
+.LP
+Here are some examples of
+.B TZ
+values that directly specify the timezone; they use some of the
+extensions to POSIX.
+.TP
+.B EST5
+stands for US Eastern Standard
+Time (EST), 5 hours behind UT, without daylight saving.
+.TP
+.B <+12>\*-12<+13>,M11.1.0,M1.2.1/147
+stands for Fiji time, 12 hours ahead
+of UT, springing forward on November's first Sunday at 02:00, and
+falling back on January's second Monday at 147:00 (i.e., 03:00 on the
+first Sunday on or after January 14).  The abbreviations for standard
+and daylight saving time are
+.q "+12"
+and
+.q "+13".
+.TP
+.B IST\*-2IDT,M3.4.4/26,M10.5.0
+stands for Israel Standard Time (IST) and Israel Daylight Time (IDT),
+2 hours ahead of UT, springing forward on March's fourth
+Thursday at 26:00 (i.e., 02:00 on the first Friday on or after March
+23), and falling back on October's last Sunday at 02:00.
+.TP
+.B <\*-04>4<\*-03>,J1/0,J365/25
+stands for permanent daylight saving time, 3 hours behind UT with
+abbreviation
+.q "\*-03".
+There is a dummy fall-back transition on December 31 at 25:00 daylight
+saving time (i.e., 24:00 standard time, equivalent to January 1 at
+00:00 standard time), and a simultaneous spring-forward transition on
+January 1 at 00:00 standard time, so daylight saving time is in effect
+all year and the initial
+.B <\*-04>
+is a placeholder.
+.TP
+.B <\*-03>3<\*-02>,M3.5.0/\*-2,M10.5.0/\*-1
+stands for time in western Greenland, 3 hours behind UT, where clocks
+follow the EU rules of
+springing forward on March's last Sunday at 01:00 UT (\-02:00 local
+time, i.e., 22:00 the previous day) and falling back on October's last
+Sunday at 01:00 UT (\-01:00 local time, i.e., 23:00 the previous day).
+The abbreviations for standard and daylight saving time are
+.q "\*-03"
+and
+.q "\*-02".
+.PP
+If no
+.I rule
+is present in
+.BR TZ ,
+the rules specified
+by the
+.BR tzfile (5)-format
+file
+.B posixrules
+in the system time conversion information directory are used, with the
+standard and daylight saving time offsets from UT replaced by those specified by
+the
+.I offset
+values in
+.BR TZ .
+.PP
+For compatibility with System V Release 3.1, a semicolon
+.RB ( ; )
+may be used to separate the
+.I rule
+from the rest of the specification.
+.SH FILES
+.ta \w'/usr/share/zoneinfo/posixrules\0\0'u
+/usr/share/zoneinfo	timezone information directory
+.br
+/usr/share/zoneinfo/localtime	local timezone file
+.br
+/usr/share/zoneinfo/posixrules	used with POSIX-style TZ
+.br
+/usr/share/zoneinfo/GMT	for UTC leap seconds
+.sp
+If
+.B /usr/share/zoneinfo/GMT
+is absent,
+UTC leap seconds are loaded from
+.BR /usr/share/zoneinfo/posixrules .
+.SH SEE ALSO
+getenv(3),
+newctime(3),
+newstrftime(3),
+time(2),
+tzfile(5)
diff --git a/contrib/tzcode/private.h b/contrib/tzcode/private.h
new file mode 100644
index 000000000000..0bb70056a9d7
--- /dev/null
+++ b/contrib/tzcode/private.h
@@ -0,0 +1,957 @@
+/* Private header for tzdb code.  */
+
+#ifndef PRIVATE_H
+
+#define PRIVATE_H
+
+/*
+** This file is in the public domain, so clarified as of
+** 1996-06-05 by Arthur David Olson.
+**
+** $FreeBSD$
+*/
+
+/* Stuff moved from Makefile.inc to reduce clutter */
+#ifndef TM_GMTOFF
+#define TM_GMTOFF	tm_gmtoff
+#define TM_ZONE		tm_zone
+#define PCTS		1
+#define HAVE_LONG_DOUBLE 1
+#define	HAVE_UNISTD_H	1
+#define	LOCALE_HOME	_PATH_LOCALE
+#define TZDIR		"/usr/share/zoneinfo"
+#endif /* ndef TM_GMTOFF */
+
+/*
+** This header is for use ONLY with the time conversion code.
+** There is no guarantee that it will remain unchanged,
+** or that it will remain at all.
+** Do NOT copy it to any system include directory.
+** Thank you!
+*/
+
+#ifndef __STDC_VERSION__
+# define __STDC_VERSION__ 0
+#endif
+
+/* Define true, false and bool if they don't work out of the box.  */
+#if __STDC_VERSION__ < 199901
+# define true 1
+# define false 0
+# define bool int
+#elif __STDC_VERSION__ < 202311
+# include <stdbool.h>
+#endif
+
+/*
+** zdump has been made independent of the rest of the time
+** conversion package to increase confidence in the verification it provides.
+** You can use zdump to help in verifying other implementations.
+** To do this, compile with -DUSE_LTZ=0 and link without the tz library.
+*/
+#ifndef USE_LTZ
+# define USE_LTZ 1
+#endif
+
+/* This string was in the Factory zone through version 2016f.  */
+#define GRANDPARENTED	"Local time zone must be set--use tzsetup"
+
+/*
+** Defaults for preprocessor symbols.
+** You can override these in your C compiler options, e.g. '-DHAVE_GETTEXT=1'.
+*/
+
+#ifndef HAVE_DECL_ASCTIME_R
+# define HAVE_DECL_ASCTIME_R 1
+#endif
+
+#if !defined HAVE_GENERIC && defined __has_extension
+# if __has_extension(c_generic_selections)
+#  define HAVE_GENERIC 1
+# else
+#  define HAVE_GENERIC 0
+# endif
+#endif
+/* _Generic is buggy in pre-4.9 GCC.  */
+#if !defined HAVE_GENERIC && defined __GNUC__ && !defined __STRICT_ANSI__
+# define HAVE_GENERIC (4 < __GNUC__ + (9 <= __GNUC_MINOR__))
+#endif
+#ifndef HAVE_GENERIC
+# define HAVE_GENERIC (201112 <= __STDC_VERSION__)
+#endif
+
+#if !defined HAVE_GETTEXT && defined __has_include
+# if __has_include(<libintl.h>)
+#  define HAVE_GETTEXT true
+# endif
+#endif
+#ifndef HAVE_GETTEXT
+# define HAVE_GETTEXT false
+#endif
+
+#ifndef HAVE_INCOMPATIBLE_CTIME_R
+# define HAVE_INCOMPATIBLE_CTIME_R 0
+#endif
+
+#ifndef HAVE_LINK
+# define HAVE_LINK 1
+#endif /* !defined HAVE_LINK */
+
+#ifndef HAVE_MALLOC_ERRNO
+# define HAVE_MALLOC_ERRNO 1
+#endif
+
+#ifndef HAVE_POSIX_DECLS
+# define HAVE_POSIX_DECLS 1
+#endif
+
+#ifndef HAVE_SETENV
+# define HAVE_SETENV 1
+#endif
+
+#ifndef HAVE_STRDUP
+# define HAVE_STRDUP 1
+#endif
+
+#ifndef HAVE_STRTOLL
+# define HAVE_STRTOLL 1
+#endif
+
+#ifndef HAVE_SYMLINK
+# define HAVE_SYMLINK 1
+#endif /* !defined HAVE_SYMLINK */
+
+#if !defined HAVE_SYS_STAT_H && defined __has_include
+# if !__has_include(<sys/stat.h>)
+#  define HAVE_SYS_STAT_H false
+# endif
+#endif
+#ifndef HAVE_SYS_STAT_H
+# define HAVE_SYS_STAT_H true
+#endif
+
+#if !defined HAVE_UNISTD_H && defined __has_include
+# if !__has_include(<unistd.h>)
+#  define HAVE_UNISTD_H false
+# endif
+#endif
+#ifndef HAVE_UNISTD_H
+# define HAVE_UNISTD_H true
+#endif
+
+#ifndef NETBSD_INSPIRED
+# define NETBSD_INSPIRED 1
+#endif
+
+#if HAVE_INCOMPATIBLE_CTIME_R
+# define asctime_r _incompatible_asctime_r
+# define ctime_r _incompatible_ctime_r
+#endif /* HAVE_INCOMPATIBLE_CTIME_R */
+
+/* Enable tm_gmtoff, tm_zone, and environ on GNUish systems.  */
+#define _GNU_SOURCE 1
+/* Fix asctime_r on Solaris 11.  */
+#define _POSIX_PTHREAD_SEMANTICS 1
+/* Enable strtoimax on pre-C99 Solaris 11.  */
+#define __EXTENSIONS__ 1
+
+/* On GNUish systems where time_t might be 32 or 64 bits, use 64.
+   On these platforms _FILE_OFFSET_BITS must also be 64; otherwise
+   setting _TIME_BITS to 64 does not work.  The code does not
+   otherwise rely on _FILE_OFFSET_BITS being 64, since it does not
+   use off_t or functions like 'stat' that depend on off_t.  */
+#ifndef _FILE_OFFSET_BITS
+# define _FILE_OFFSET_BITS 64
+#endif
+#if !defined _TIME_BITS && _FILE_OFFSET_BITS == 64
+# define _TIME_BITS 64
+#endif
+
+/*
+** Nested includes
+*/
+
+/* Avoid clashes with NetBSD by renaming NetBSD's declarations.
+   If defining the 'timezone' variable, avoid a clash with FreeBSD's
+   'timezone' function by renaming its declaration.  */
+#define localtime_rz sys_localtime_rz
+#define mktime_z sys_mktime_z
+#define posix2time_z sys_posix2time_z
+#define time2posix_z sys_time2posix_z
+#if defined USG_COMPAT && USG_COMPAT == 2
+# define timezone sys_timezone
+#endif
+#define timezone_t sys_timezone_t
+#define tzalloc sys_tzalloc
+#define tzfree sys_tzfree
+#include <time.h>
+#undef localtime_rz
+#undef mktime_z
+#undef posix2time_z
+#undef time2posix_z
+#if defined USG_COMPAT && USG_COMPAT == 2
+# undef timezone
+#endif
+#undef timezone_t
+#undef tzalloc
+#undef tzfree
+
+#include <stddef.h>
+#include <string.h>
+#include <limits.h>	/* for CHAR_BIT et al. */
+#include <stdlib.h>
+
+#include <errno.h>
+
+#ifndef EINVAL
+# define EINVAL ERANGE
+#endif
+
+#ifndef ELOOP
+# define ELOOP EINVAL
+#endif
+#ifndef ENAMETOOLONG
+# define ENAMETOOLONG EINVAL
+#endif
+#ifndef ENOMEM
+# define ENOMEM EINVAL
+#endif
+#ifndef ENOTSUP
+# define ENOTSUP EINVAL
+#endif
+#ifndef EOVERFLOW
+# define EOVERFLOW EINVAL
+#endif
+
+#if HAVE_GETTEXT
+# include <libintl.h>
+#endif /* HAVE_GETTEXT */
+
+#if HAVE_UNISTD_H
+# include <unistd.h> /* for R_OK, and other POSIX goodness */
+#endif /* HAVE_UNISTD_H */
+
+#ifndef HAVE_STRFTIME_L
+# if _POSIX_VERSION < 200809
+#  define HAVE_STRFTIME_L 0
+# else
+#  define HAVE_STRFTIME_L 1
+# endif
+#endif
+
+#ifndef USG_COMPAT
+# ifndef _XOPEN_VERSION
+#  define USG_COMPAT 0
+# else
+#  define USG_COMPAT 1
+# endif
+#endif
+
+#ifndef HAVE_TZNAME
+# if _POSIX_VERSION < 198808 && !USG_COMPAT
+#  define HAVE_TZNAME 0
+# else
+#  define HAVE_TZNAME 1
+# endif
+#endif
+
+#ifndef ALTZONE
+# if defined __sun || defined _M_XENIX
+#  define ALTZONE 1
+# else
+#  define ALTZONE 0
+# endif
+#endif
+
+#ifndef R_OK
+# define R_OK 4
+#endif /* !defined R_OK */
+
+/*
+** Define HAVE_STDINT_H's default value here, rather than at the
+** start, since __GLIBC__ and INTMAX_MAX's values depend on
+** previously-included files.  glibc 2.1 and Solaris 10 and later have
+** stdint.h, even with pre-C99 compilers.
+*/
+#if !defined HAVE_STDINT_H && defined __has_include
+# define HAVE_STDINT_H true /* C23 __has_include implies C99 stdint.h.  */
+#endif
+#ifndef HAVE_STDINT_H
+# define HAVE_STDINT_H \
+   (199901 <= __STDC_VERSION__ \
+    || 2 < __GLIBC__ + (1 <= __GLIBC_MINOR__) \
+    || __CYGWIN__ || INTMAX_MAX)
+#endif /* !defined HAVE_STDINT_H */
+
+#if HAVE_STDINT_H
+# include <stdint.h>
+#endif /* !HAVE_STDINT_H */
+
+#ifndef HAVE_INTTYPES_H
+# define HAVE_INTTYPES_H HAVE_STDINT_H
+#endif
+#if HAVE_INTTYPES_H
+# include <inttypes.h>
+#endif
+
+/* Pre-C99 GCC compilers define __LONG_LONG_MAX__ instead of LLONG_MAX.  */
+#if defined __LONG_LONG_MAX__ && !defined __STRICT_ANSI__
+# ifndef LLONG_MAX
+#  define LLONG_MAX __LONG_LONG_MAX__
+# endif
+# ifndef LLONG_MIN
+#  define LLONG_MIN (-1 - LLONG_MAX)
+# endif
+# ifndef ULLONG_MAX
+#  define ULLONG_MAX (LLONG_MAX * 2ull + 1)
+# endif
+#endif
+
+#ifndef INT_FAST64_MAX
+# if 1 <= LONG_MAX >> 31 >> 31
+typedef long int_fast64_t;
+#  define INT_FAST64_MIN LONG_MIN
+#  define INT_FAST64_MAX LONG_MAX
+# else
+/* If this fails, compile with -DHAVE_STDINT_H or with a better compiler.  */
+typedef long long int_fast64_t;
+#  define INT_FAST64_MIN LLONG_MIN
+#  define INT_FAST64_MAX LLONG_MAX
+# endif
+#endif
+
+#ifndef PRIdFAST64
+# if INT_FAST64_MAX == LONG_MAX
+#  define PRIdFAST64 "ld"
+# else
+#  define PRIdFAST64 "lld"
+# endif
+#endif
+
+#ifndef SCNdFAST64
+# define SCNdFAST64 PRIdFAST64
+#endif
+
+#ifndef INT_FAST32_MAX
+# if INT_MAX >> 31 == 0
+typedef long int_fast32_t;
+#  define INT_FAST32_MAX LONG_MAX
+#  define INT_FAST32_MIN LONG_MIN
+# else
+typedef int int_fast32_t;
+#  define INT_FAST32_MAX INT_MAX
+#  define INT_FAST32_MIN INT_MIN
+# endif
+#endif
+
+#ifndef INTMAX_MAX
+# ifdef LLONG_MAX
+typedef long long intmax_t;
+#  if HAVE_STRTOLL
+#   define strtoimax strtoll
+#  endif
+#  define INTMAX_MAX LLONG_MAX
+#  define INTMAX_MIN LLONG_MIN
+# else
+typedef long intmax_t;
+#  define INTMAX_MAX LONG_MAX
+#  define INTMAX_MIN LONG_MIN
+# endif
+# ifndef strtoimax
+#  define strtoimax strtol
+# endif
+#endif
+
+#ifndef PRIdMAX
+# if INTMAX_MAX == LLONG_MAX
+#  define PRIdMAX "lld"
+# else
+#  define PRIdMAX "ld"
+# endif
+#endif
+
+#ifndef PTRDIFF_MAX
+# define PTRDIFF_MAX MAXVAL(ptrdiff_t, TYPE_BIT(ptrdiff_t))
+#endif
+
+#ifndef UINT_FAST32_MAX
+typedef unsigned long uint_fast32_t;
+#endif
+
+#ifndef UINT_FAST64_MAX
+# if 3 <= ULONG_MAX >> 31 >> 31
+typedef unsigned long uint_fast64_t;
+#  define UINT_FAST64_MAX ULONG_MAX
+# else
+/* If this fails, compile with -DHAVE_STDINT_H or with a better compiler.  */
+typedef unsigned long long uint_fast64_t;
+#  define UINT_FAST64_MAX ULLONG_MAX
+# endif
+#endif
+
+#ifndef UINTMAX_MAX
+# ifdef ULLONG_MAX
+typedef unsigned long long uintmax_t;
+# else
+typedef unsigned long uintmax_t;
+# endif
+#endif
+
+#ifndef PRIuMAX
+# ifdef ULLONG_MAX
+#  define PRIuMAX "llu"
+# else
+#  define PRIuMAX "lu"
+# endif
+#endif
+
+#ifndef SIZE_MAX
+# define SIZE_MAX ((size_t) -1)
+#endif
+
+/* Support ckd_add, ckd_sub, ckd_mul on C23 or recent-enough GCC-like
+   hosts, unless compiled with -DHAVE_STDCKDINT_H=0 or with pre-C23 EDG.  */
+#if !defined HAVE_STDCKDINT_H && defined __has_include
+# if __has_include(<stdckdint.h>)
+#  define HAVE_STDCKDINT_H true
+# endif
+#endif
+#ifdef HAVE_STDCKDINT_H
+# if HAVE_STDCKDINT_H
+#  include <stdckdint.h>
+# endif
+#elif defined __EDG__
+/* Do nothing, to work around EDG bug <https://bugs.gnu.org/53256>.  */
+#elif defined __has_builtin
+# if __has_builtin(__builtin_add_overflow)
+#  define ckd_add(r, a, b) __builtin_add_overflow(a, b, r)
+# endif
+# if __has_builtin(__builtin_sub_overflow)
+#  define ckd_sub(r, a, b) __builtin_sub_overflow(a, b, r)
+# endif
+# if __has_builtin(__builtin_mul_overflow)
+#  define ckd_mul(r, a, b) __builtin_mul_overflow(a, b, r)
+# endif
+#elif 7 <= __GNUC__
+# define ckd_add(r, a, b) __builtin_add_overflow(a, b, r)
+# define ckd_sub(r, a, b) __builtin_sub_overflow(a, b, r)
+# define ckd_mul(r, a, b) __builtin_mul_overflow(a, b, r)
+#endif
+
+#if 3 <= __GNUC__
+# define ATTRIBUTE_MALLOC __attribute__((malloc))
+# define ATTRIBUTE_FORMAT(spec) __attribute__((format spec))
+#else
+# define ATTRIBUTE_MALLOC /* empty */
+# define ATTRIBUTE_FORMAT(spec) /* empty */
+#endif
+
+#if (defined __has_c_attribute \
+     && (202311 <= __STDC_VERSION__ || !defined __STRICT_ANSI__))
+# define HAVE_HAS_C_ATTRIBUTE true
+#else
+# define HAVE_HAS_C_ATTRIBUTE false
+#endif
+
+#if HAVE_HAS_C_ATTRIBUTE
+# if __has_c_attribute(fallthrough)
+#  define ATTRIBUTE_FALLTHROUGH [[fallthrough]]
+# endif
+#endif
+#ifndef ATTRIBUTE_FALLTHROUGH
+# if 7 <= __GNUC__
+#  define ATTRIBUTE_FALLTHROUGH __attribute__((fallthrough))
+# else
+#  define ATTRIBUTE_FALLTHROUGH ((void) 0)
+# endif
+#endif
+
+#if HAVE_HAS_C_ATTRIBUTE
+# if __has_c_attribute(maybe_unused)
+#  define ATTRIBUTE_MAYBE_UNUSED [[maybe_unused]]
+# endif
+#endif
+#ifndef ATTRIBUTE_MAYBE_UNUSED
+# if 2 < __GNUC__ + (7 <= __GNUC_MINOR__)
+#  define ATTRIBUTE_MAYBE_UNUSED __attribute__((unused))
+# else
+#  define ATTRIBUTE_MAYBE_UNUSED /* empty */
+# endif
+#endif
+
+#if HAVE_HAS_C_ATTRIBUTE
+# if __has_c_attribute(noreturn)
+#  define ATTRIBUTE_NORETURN [[noreturn]]
+# endif
+#endif
+#ifndef ATTRIBUTE_NORETURN
+# if 201112 <= __STDC_VERSION__
+#  define ATTRIBUTE_NORETURN _Noreturn
+# elif 2 < __GNUC__ + (8 <= __GNUC_MINOR__)
+#  define ATTRIBUTE_NORETURN __attribute__((noreturn))
+# else
+#  define ATTRIBUTE_NORETURN /* empty */
+# endif
+#endif
+
+#if HAVE_HAS_C_ATTRIBUTE
+# if __has_c_attribute(reproducible)
+#  define ATTRIBUTE_REPRODUCIBLE [[reproducible]]
+# endif
+#endif
+#ifndef ATTRIBUTE_REPRODUCIBLE
+# if 3 <= __GNUC__
+#  define ATTRIBUTE_REPRODUCIBLE __attribute__((pure))
+# else
+#  define ATTRIBUTE_REPRODUCIBLE /* empty */
+# endif
+#endif
+
+#if HAVE_HAS_C_ATTRIBUTE
+# if __has_c_attribute(unsequenced)
+#  define ATTRIBUTE_UNSEQUENCED [[unsequenced]]
+# endif
+#endif
+#ifndef ATTRIBUTE_UNSEQUENCED
+# if 3 <= __GNUC__
+#  define ATTRIBUTE_UNSEQUENCED __attribute__((const))
+# else
+#  define ATTRIBUTE_UNSEQUENCED /* empty */
+# endif
+#endif
+
+#if __STDC_VERSION__ < 199901 && !defined restrict
+# define restrict /* empty */
+#endif
+
+#if 2 < __GNUC__ || (__GNUC__ == 2 && 96 <= __GNUC_MINOR__)
+# define ATTRIBUTE_PURE __attribute__ ((__pure__))
+#else
+# define ATTRIBUTE_PURE /* empty */
+#endif
+
+/*
+** Workarounds for compilers/systems.
+*/
+
+#ifndef EPOCH_LOCAL
+# define EPOCH_LOCAL 0
+#endif
+#ifndef EPOCH_OFFSET
+# define EPOCH_OFFSET 0
+#endif
+#ifndef RESERVE_STD_EXT_IDS
+# define RESERVE_STD_EXT_IDS 0
+#endif
+
+/* If standard C identifiers with external linkage (e.g., localtime)
+   are reserved and are not already being renamed anyway, rename them
+   as if compiling with '-Dtime_tz=time_t'.  */
+#if !defined time_tz && RESERVE_STD_EXT_IDS && USE_LTZ
+# define time_tz time_t
+#endif
+
+/*
+** Compile with -Dtime_tz=T to build the tz package with a private
+** time_t type equivalent to T rather than the system-supplied time_t.
+** This debugging feature can test unusual design decisions
+** (e.g., time_t wider than 'long', or unsigned time_t) even on
+** typical platforms.
+*/
+#if defined time_tz || EPOCH_LOCAL || EPOCH_OFFSET != 0
+# define TZ_TIME_T 1
+#else
+# define TZ_TIME_T 0
+#endif
+
+#if defined LOCALTIME_IMPLEMENTATION && TZ_TIME_T
+static time_t sys_time(time_t *x) { return time(x); }
+#endif
+
+#if TZ_TIME_T
+
+typedef time_tz tz_time_t;
+
+# undef  asctime
+# define asctime tz_asctime
+# undef  asctime_r
+# define asctime_r tz_asctime_r
+# undef  ctime
+# define ctime tz_ctime
+# undef  ctime_r
+# define ctime_r tz_ctime_r
+# undef  difftime
+# define difftime tz_difftime
+# undef  gmtime
+# define gmtime tz_gmtime
+# undef  gmtime_r
+# define gmtime_r tz_gmtime_r
+# undef  localtime
+# define localtime tz_localtime
+# undef  localtime_r
+# define localtime_r tz_localtime_r
+# undef  localtime_rz
+# define localtime_rz tz_localtime_rz
+# undef  mktime
+# define mktime tz_mktime
+# undef  mktime_z
+# define mktime_z tz_mktime_z
+# undef  offtime
+# define offtime tz_offtime
+# undef  posix2time
+# define posix2time tz_posix2time
+# undef  posix2time_z
+# define posix2time_z tz_posix2time_z
+# undef  strftime
+# define strftime tz_strftime
+# undef  time
+# define time tz_time
+# undef  time2posix
+# define time2posix tz_time2posix
+# undef  time2posix_z
+# define time2posix_z tz_time2posix_z
+# undef  time_t
+# define time_t tz_time_t
+# undef  timegm
+# define timegm tz_timegm
+# undef  timelocal
+# define timelocal tz_timelocal
+# undef  timeoff
+# define timeoff tz_timeoff
+# undef  tzalloc
+# define tzalloc tz_tzalloc
+# undef  tzfree
+# define tzfree tz_tzfree
+# undef  tzset
+# define tzset tz_tzset
+# if HAVE_STRFTIME_L
+#  undef  strftime_l
+#  define strftime_l tz_strftime_l
+# endif
+# if HAVE_TZNAME
+#  undef  tzname
+#  define tzname tz_tzname
+# endif
+# if USG_COMPAT
+#  undef  daylight
+#  define daylight tz_daylight
+#  undef  timezone
+#  define timezone tz_timezone
+# endif
+# if ALTZONE
+#  undef  altzone
+#  define altzone tz_altzone
+# endif
+
+char *asctime(struct tm const *);
+char *asctime_r(struct tm const *restrict, char *restrict);
+char *ctime(time_t const *);
+char *ctime_r(time_t const *, char *);
+double difftime(time_t, time_t) ATTRIBUTE_UNSEQUENCED;
+size_t strftime(char *restrict, size_t, char const *restrict,
+		struct tm const *restrict);
+# if HAVE_STRFTIME_L
+size_t strftime_l(char *restrict, size_t, char const *restrict,
+		  struct tm const *restrict, locale_t);
+# endif
+struct tm *gmtime(time_t const *);
+struct tm *gmtime_r(time_t const *restrict, struct tm *restrict);
+struct tm *localtime(time_t const *);
+struct tm *localtime_r(time_t const *restrict, struct tm *restrict);
+time_t mktime(struct tm *);
+time_t time(time_t *);
+time_t timegm(struct tm *);
+void tzset(void);
+#endif
+
+#ifndef HAVE_DECL_TIMEGM
+# if (202311 <= __STDC_VERSION__ \
+      || defined __GLIBC__ || defined __tm_zone /* musl */ \
+      || defined __FreeBSD__ || defined __NetBSD__ || defined __OpenBSD__ \
+      || (defined __APPLE__ && defined __MACH__))
+#  define HAVE_DECL_TIMEGM true
+# else
+#  define HAVE_DECL_TIMEGM false
+# endif
+#endif
+#if !HAVE_DECL_TIMEGM && !defined timegm
+time_t timegm(struct tm *);
+#endif
+
+#if !HAVE_DECL_ASCTIME_R && !defined asctime_r
+extern char *asctime_r(struct tm const *restrict, char *restrict);
+#endif
+
+#ifndef HAVE_DECL_ENVIRON
+# if defined environ || defined __USE_GNU
+#  define HAVE_DECL_ENVIRON 1
+# else
+#  define HAVE_DECL_ENVIRON 0
+# endif
+#endif
+
+#if !HAVE_DECL_ENVIRON
+extern char **environ;
+#endif
+
+#if 2 <= HAVE_TZNAME + (TZ_TIME_T || !HAVE_POSIX_DECLS)
+extern char *tzname[];
+#endif
+#if 2 <= USG_COMPAT + (TZ_TIME_T || !HAVE_POSIX_DECLS)
+extern long timezone;
+extern int daylight;
+#endif
+#if 2 <= ALTZONE + (TZ_TIME_T || !HAVE_POSIX_DECLS)
+extern long altzone;
+#endif
+
+/*
+** The STD_INSPIRED functions are similar, but most also need
+** declarations if time_tz is defined.
+*/
+
+#ifdef STD_INSPIRED
+# if TZ_TIME_T || !defined offtime
+struct tm *offtime(time_t const *, long);
+# endif
+# if TZ_TIME_T || !defined timelocal
+time_t timelocal(struct tm *);
+# endif
+# if TZ_TIME_T || !defined timeoff
+time_t timeoff(struct tm *, long);
+# endif
+# if TZ_TIME_T || !defined time2posix
+time_t time2posix(time_t);
+# endif
+# if TZ_TIME_T || !defined posix2time
+time_t posix2time(time_t);
+# endif
+#endif
+
+/* Infer TM_ZONE on systems where this information is known, but suppress
+   guessing if NO_TM_ZONE is defined.  Similarly for TM_GMTOFF.  */
+#if (defined __GLIBC__ \
+     || defined __tm_zone /* musl */ \
+     || defined __FreeBSD__ || defined __NetBSD__ || defined __OpenBSD__ \
+     || (defined __APPLE__ && defined __MACH__))
+# if !defined TM_GMTOFF && !defined NO_TM_GMTOFF
+#  define TM_GMTOFF tm_gmtoff
+# endif
+# if !defined TM_ZONE && !defined NO_TM_ZONE
+#  define TM_ZONE tm_zone
+# endif
+#endif
+
+/*
+** Define functions that are ABI compatible with NetBSD but have
+** better prototypes.  NetBSD 6.1.4 defines a pointer type timezone_t
+** and labors under the misconception that 'const timezone_t' is a
+** pointer to a constant.  This use of 'const' is ineffective, so it
+** is not done here.  What we call 'struct state' NetBSD calls
+** 'struct __state', but this is a private name so it doesn't matter.
+*/
+#if NETBSD_INSPIRED
+typedef struct state *timezone_t;
+struct tm *localtime_rz(timezone_t restrict, time_t const *restrict,
+			struct tm *restrict);
+time_t mktime_z(timezone_t restrict, struct tm *restrict);
+timezone_t tzalloc(char const *);
+void tzfree(timezone_t);
+# ifdef STD_INSPIRED
+#  if TZ_TIME_T || !defined posix2time_z
+time_t posix2time_z(timezone_t, time_t) ATTRIBUTE_REPRODUCIBLE;
+#  endif
+#  if TZ_TIME_T || !defined time2posix_z
+time_t time2posix_z(timezone_t, time_t) ATTRIBUTE_REPRODUCIBLE;
+#  endif
+# endif
+#endif
+
+/*
+** Finally, some convenience items.
+*/
+
+#define TYPE_BIT(type)	(sizeof(type) * CHAR_BIT)
+#define TYPE_SIGNED(type) (((type) -1) < 0)
+#define TWOS_COMPLEMENT(t) ((t) ~ (t) 0 < 0)
+
+/* Minimum and maximum of two values.  Use lower case to avoid
+   naming clashes with standard include files.  */
+#define max(a, b) ((a) > (b) ? (a) : (b))
+#define min(a, b) ((a) < (b) ? (a) : (b))
+
+/* Max and min values of the integer type T, of which only the bottom
+   B bits are used, and where the highest-order used bit is considered
+   to be a sign bit if T is signed.  */
+#define MAXVAL(t, b)						\
+  ((t) (((t) 1 << ((b) - 1 - TYPE_SIGNED(t)))			\
+	- 1 + ((t) 1 << ((b) - 1 - TYPE_SIGNED(t)))))
+#define MINVAL(t, b)						\
+  ((t) (TYPE_SIGNED(t) ? - TWOS_COMPLEMENT(t) - MAXVAL(t, b) : 0))
+
+/* The extreme time values, assuming no padding.  */
+#define TIME_T_MIN_NO_PADDING MINVAL(time_t, TYPE_BIT(time_t))
+#define TIME_T_MAX_NO_PADDING MAXVAL(time_t, TYPE_BIT(time_t))
+
+/* The extreme time values.  These are macros, not constants, so that
+   any portability problems occur only when compiling .c files that use
+   the macros, which is safer for applications that need only zdump and zic.
+   This implementation assumes no padding if time_t is signed and
+   either the compiler lacks support for _Generic or time_t is not one
+   of the standard signed integer types.  */
+#if HAVE_GENERIC
+# define TIME_T_MIN \
+    _Generic((time_t) 0, \
+	     signed char: SCHAR_MIN, short: SHRT_MIN, \
+	     int: INT_MIN, long: LONG_MIN, long long: LLONG_MIN, \
+	     default: TIME_T_MIN_NO_PADDING)
+# define TIME_T_MAX \
+    (TYPE_SIGNED(time_t) \
+     ? _Generic((time_t) 0, \
+		signed char: SCHAR_MAX, short: SHRT_MAX, \
+		int: INT_MAX, long: LONG_MAX, long long: LLONG_MAX, \
+		default: TIME_T_MAX_NO_PADDING)			    \
+     : (time_t) -1)
+#else
+# define TIME_T_MIN TIME_T_MIN_NO_PADDING
+# define TIME_T_MAX TIME_T_MAX_NO_PADDING
+#endif
+
+/*
+** 302 / 1000 is log10(2.0) rounded up.
+** Subtract one for the sign bit if the type is signed;
+** add one for integer division truncation;
+** add one more for a minus sign if the type is signed.
+*/
+#define INT_STRLEN_MAXIMUM(type) \
+	((TYPE_BIT(type) - TYPE_SIGNED(type)) * 302 / 1000 + \
+	1 + TYPE_SIGNED(type))
+
+/*
+** INITIALIZE(x)
+*/
+
+#ifdef GCC_LINT
+# define INITIALIZE(x)	((x) = 0)
+#else
+# define INITIALIZE(x)
+#endif
+
+/* Whether memory access must strictly follow the C standard.
+   If 0, it's OK to read uninitialized storage so long as the value is
+   not relied upon.  Defining it to 0 lets mktime access parts of
+   struct tm that might be uninitialized, as a heuristic when the
+   standard doesn't say what to return and when tm_gmtoff can help
+   mktime likely infer a better value.  */
+#ifndef UNINIT_TRAP
+# define UNINIT_TRAP 0
+#endif
+
+#ifdef DEBUG
+# undef unreachable
+# define unreachable() abort()
+#elif !defined unreachable
+# ifdef __has_builtin
+#  if __has_builtin(__builtin_unreachable)
+#   define unreachable() __builtin_unreachable()
+#  endif
+# elif 4 < __GNUC__ + (5 <= __GNUC_MINOR__)
+#  define unreachable() __builtin_unreachable()
+# endif
+# ifndef unreachable
+#  define unreachable() ((void) 0)
+# endif
+#endif
+
+/*
+** For the benefit of GNU folk...
+** '_(MSGID)' uses the current locale's message library string for MSGID.
+** The default is to use gettext if available, and use MSGID otherwise.
+*/
+
+#if HAVE_GETTEXT
+#define _(msgid) gettext(msgid)
+#else /* !HAVE_GETTEXT */
+#define _(msgid) msgid
+#endif /* !HAVE_GETTEXT */
+
+#if !defined TZ_DOMAIN && defined HAVE_GETTEXT
+# define TZ_DOMAIN "tz"
+#endif
+
+#if HAVE_INCOMPATIBLE_CTIME_R
+#undef asctime_r
+#undef ctime_r
+char *asctime_r(struct tm const *, char *);
+char *ctime_r(time_t const *, char *);
+#endif /* HAVE_INCOMPATIBLE_CTIME_R */
+
+/* Handy macros that are independent of tzfile implementation.  */
+
+enum {
+  SECSPERMIN = 60,
+  MINSPERHOUR = 60,
+  SECSPERHOUR = SECSPERMIN * MINSPERHOUR,
+  HOURSPERDAY = 24,
+  DAYSPERWEEK = 7,
+  DAYSPERNYEAR = 365,
+  DAYSPERLYEAR = DAYSPERNYEAR + 1,
+  MONSPERYEAR = 12,
+  YEARSPERREPEAT = 400	/* years before a Gregorian repeat */
+};
+
+#define SECSPERDAY	((int_fast32_t) SECSPERHOUR * HOURSPERDAY)
+
+#define DAYSPERREPEAT		((int_fast32_t) 400 * 365 + 100 - 4 + 1)
+#define SECSPERREPEAT		((int_fast64_t) DAYSPERREPEAT * SECSPERDAY)
+#define AVGSECSPERYEAR		(SECSPERREPEAT / YEARSPERREPEAT)
+
+enum {
+  TM_SUNDAY,
+  TM_MONDAY,
+  TM_TUESDAY,
+  TM_WEDNESDAY,
+  TM_THURSDAY,
+  TM_FRIDAY,
+  TM_SATURDAY
+};
+
+enum {
+  TM_JANUARY,
+  TM_FEBRUARY,
+  TM_MARCH,
+  TM_APRIL,
+  TM_MAY,
+  TM_JUNE,
+  TM_JULY,
+  TM_AUGUST,
+  TM_SEPTEMBER,
+  TM_OCTOBER,
+  TM_NOVEMBER,
+  TM_DECEMBER
+};
+
+enum {
+  TM_YEAR_BASE = 1900,
+  TM_WDAY_BASE = TM_MONDAY,
+  EPOCH_YEAR = 1970,
+  EPOCH_WDAY = TM_THURSDAY
+};
+
+#define isleap(y) (((y) % 4) == 0 && (((y) % 100) != 0 || ((y) % 400) == 0))
+
+/*
+** Since everything in isleap is modulo 400 (or a factor of 400), we know that
+**	isleap(y) == isleap(y % 400)
+** and so
+**	isleap(a + b) == isleap((a + b) % 400)
+** or
+**	isleap(a + b) == isleap(a % 400 + b % 400)
+** This is true even if % means modulo rather than Fortran remainder
+** (which is allowed by C89 but not by C99 or later).
+** We use this to avoid addition overflow problems.
+*/
+
+#define isleap_sum(a, b)	isleap((a) % 400 + (b) % 400)
+
+#endif /* !defined PRIVATE_H */
diff --git a/contrib/tzcode/stdtime/difftime.c b/contrib/tzcode/stdtime/difftime.c
deleted file mode 100644
index 0480849c3ffe..000000000000
--- a/contrib/tzcode/stdtime/difftime.c
+++ /dev/null
@@ -1,67 +0,0 @@
-/*
-** This file is in the public domain, so clarified as of
-** 1996-06-05 by Arthur David Olson.
-*/
-
-#include <sys/cdefs.h>
-#ifndef lint
-#ifndef NOID
-static char	elsieid[] __unused = "@(#)difftime.c	8.1";
-#endif /* !defined NOID */
-#endif /* !defined lint */
-__FBSDID("$FreeBSD$");
-
-/*LINTLIBRARY*/
-
-#include "namespace.h"
-#include "private.h"	/* for time_t, TYPE_INTEGRAL, and TYPE_SIGNED */
-#include "un-namespace.h"
-
-double
-difftime(const time_t time1, const time_t time0)
-{
-	/*
-	** If (sizeof (double) > sizeof (time_t)) simply convert and subtract
-	** (assuming that the larger type has more precision).
-	** This is the common real-world case circa 2004.
-	*/
-	if (sizeof (double) > sizeof (time_t))
-		return (double) time1 - (double) time0;
-	if (!TYPE_INTEGRAL(time_t)) {
-		/*
-		** time_t is floating.
-		*/
-		return time1 - time0;
-	}
-	if (!TYPE_SIGNED(time_t)) {
-		/*
-		** time_t is integral and unsigned.
-		** The difference of two unsigned values can't overflow
-		** if the minuend is greater than or equal to the subtrahend.
-		*/
-		if (time1 >= time0)
-			return time1 - time0;
-		else	return -((double) (time0 - time1));
-	}
-	/*
-	** time_t is integral and signed.
-	** Handle cases where both time1 and time0 have the same sign
-	** (meaning that their difference cannot overflow).
-	*/
-	if ((time1 < 0) == (time0 < 0))
-		return time1 - time0;
-	/*
-	** time1 and time0 have opposite signs.
-	** Punt if unsigned long is too narrow.
-	*/
-	if (sizeof (unsigned long) < sizeof (time_t))
-		return (double) time1 - (double) time0;
-	/*
-	** Stay calm...decent optimizers will eliminate the complexity below.
-	*/
-	if (time1 >= 0 /* && time0 < 0 */)
-		return (unsigned long) time1 +
-			(unsigned long) (-(time0 + 1)) + 1;
-	return -(double) ((unsigned long) time0 +
-		(unsigned long) (-(time1 + 1)) + 1);
-}
diff --git a/contrib/tzcode/stdtime/localtime.c b/contrib/tzcode/stdtime/localtime.c
deleted file mode 100644
index 6a0e0ce4fe4b..000000000000
--- a/contrib/tzcode/stdtime/localtime.c
+++ /dev/null
@@ -1,2317 +0,0 @@
-/*
-** This file is in the public domain, so clarified as of
-** 1996-06-05 by Arthur David Olson.
-*/
-
-#include <sys/cdefs.h>
-#ifndef lint
-#ifndef NOID
-static char	elsieid[] __unused = "@(#)localtime.c	8.14";
-#endif /* !defined NOID */
-#endif /* !defined lint */
-__FBSDID("$FreeBSD$");
-
-/*
-** Leap second handling from Bradley White.
-** POSIX-style TZ environment variable handling from Guy Harris.
-*/
-
-/*LINTLIBRARY*/
-
-#include "namespace.h"
-#include <sys/types.h>
-#include <sys/stat.h>
-#include <errno.h>
-#include <fcntl.h>
-#include <pthread.h>
-#include "private.h"
-#include "un-namespace.h"
-
-#include "tzfile.h"
-#include "float.h"	/* for FLT_MAX and DBL_MAX */
-
-#ifndef TZ_ABBR_MAX_LEN
-#define TZ_ABBR_MAX_LEN	16
-#endif /* !defined TZ_ABBR_MAX_LEN */
-
-#ifndef TZ_ABBR_CHAR_SET
-#define TZ_ABBR_CHAR_SET \
-	"abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789 :+-._"
-#endif /* !defined TZ_ABBR_CHAR_SET */
-
-#ifndef TZ_ABBR_ERR_CHAR
-#define TZ_ABBR_ERR_CHAR	'_'
-#endif /* !defined TZ_ABBR_ERR_CHAR */
-
-#include "libc_private.h"
-
-#define	_MUTEX_LOCK(x)		if (__isthreaded) _pthread_mutex_lock(x)
-#define	_MUTEX_UNLOCK(x)	if (__isthreaded) _pthread_mutex_unlock(x)
-
-#define _RWLOCK_RDLOCK(x)						\
-		do {							\
-			if (__isthreaded) _pthread_rwlock_rdlock(x);	\
-		} while (0)
-
-#define _RWLOCK_WRLOCK(x)						\
-		do {							\
-			if (__isthreaded) _pthread_rwlock_wrlock(x);	\
-		} while (0)
-
-#define _RWLOCK_UNLOCK(x)						\
-		do {							\
-			if (__isthreaded) _pthread_rwlock_unlock(x);	\
-		} while (0)
-
-/*
-** SunOS 4.1.1 headers lack O_BINARY.
-*/
-
-#ifdef O_BINARY
-#define OPEN_MODE	(O_RDONLY | O_BINARY)
-#endif /* defined O_BINARY */
-#ifndef O_BINARY
-#define OPEN_MODE	O_RDONLY
-#endif /* !defined O_BINARY */
-
-#ifndef WILDABBR
-/*
-** Someone might make incorrect use of a time zone abbreviation:
-**	1.	They might reference tzname[0] before calling tzset (explicitly
-**		or implicitly).
-**	2.	They might reference tzname[1] before calling tzset (explicitly
-**		or implicitly).
-**	3.	They might reference tzname[1] after setting to a time zone
-**		in which Daylight Saving Time is never observed.
-**	4.	They might reference tzname[0] after setting to a time zone
-**		in which Standard Time is never observed.
-**	5.	They might reference tm.TM_ZONE after calling offtime.
-** What's best to do in the above cases is open to debate;
-** for now, we just set things up so that in any of the five cases
-** WILDABBR is used. Another possibility: initialize tzname[0] to the
-** string "tzname[0] used before set", and similarly for the other cases.
-** And another: initialize tzname[0] to "ERA", with an explanation in the
-** manual page of what this "time zone abbreviation" means (doing this so
-** that tzname[0] has the "normal" length of three characters).
-*/
-#define WILDABBR	"   "
-#endif /* !defined WILDABBR */
-
-static char		wildabbr[] = WILDABBR;
-
-/*
- * In June 2004 it was decided UTC was a more appropriate default time
- * zone than GMT.
- */
-
-static const char	gmt[] = "UTC";
-
-/*
-** The DST rules to use if TZ has no rules and we can't load TZDEFRULES.
-** We default to US rules as of 1999-08-17.
-** POSIX 1003.1 section 8.1.1 says that the default DST rules are
-** implementation dependent; for historical reasons, US rules are a
-** common default.
-*/
-#ifndef TZDEFRULESTRING
-#define TZDEFRULESTRING ",M4.1.0,M10.5.0"
-#endif /* !defined TZDEFDST */
-
-struct ttinfo {				/* time type information */
-	long		tt_gmtoff;	/* UTC offset in seconds */
-	int		tt_isdst;	/* used to set tm_isdst */
-	int		tt_abbrind;	/* abbreviation list index */
-	int		tt_ttisstd;	/* TRUE if transition is std time */
-	int		tt_ttisgmt;	/* TRUE if transition is UTC */
-};
-
-struct lsinfo {				/* leap second information */
-	time_t		ls_trans;	/* transition time */
-	long		ls_corr;	/* correction to apply */
-};
-
-#define BIGGEST(a, b)	(((a) > (b)) ? (a) : (b))
-
-#ifdef TZNAME_MAX
-#define MY_TZNAME_MAX	TZNAME_MAX
-#endif /* defined TZNAME_MAX */
-#ifndef TZNAME_MAX
-#define MY_TZNAME_MAX	255
-#endif /* !defined TZNAME_MAX */
-
-struct state {
-	int		leapcnt;
-	int		timecnt;
-	int		typecnt;
-	int		charcnt;
-	int		goback;
-	int		goahead;
-	time_t		ats[TZ_MAX_TIMES];
-	unsigned char	types[TZ_MAX_TIMES];
-	struct ttinfo	ttis[TZ_MAX_TYPES];
-	char		chars[BIGGEST(BIGGEST(TZ_MAX_CHARS + 1, sizeof gmt),
-				(2 * (MY_TZNAME_MAX + 1)))];
-	struct lsinfo	lsis[TZ_MAX_LEAPS];
-};
-
-struct rule {
-	int		r_type;		/* type of rule--see below */
-	int		r_day;		/* day number of rule */
-	int		r_week;		/* week number of rule */
-	int		r_mon;		/* month number of rule */
-	long		r_time;		/* transition time of rule */
-};
-
-#define JULIAN_DAY		0	/* Jn - Julian day */
-#define DAY_OF_YEAR		1	/* n - day of year */
-#define MONTH_NTH_DAY_OF_WEEK	2	/* Mm.n.d - month, week, day of week */
-
-/*
-** Prototypes for static functions.
-*/
-
-static long		detzcode(const char * codep);
-static time_t		detzcode64(const char * codep);
-static int		differ_by_repeat(time_t t1, time_t t0);
-static const char *	getzname(const char * strp) ATTRIBUTE_PURE;
-static const char *	getqzname(const char * strp, const int delim)
-  ATTRIBUTE_PURE;
-static const char *	getnum(const char * strp, int * nump, int min,
-				int max);
-static const char *	getsecs(const char * strp, long * secsp);
-static const char *	getoffset(const char * strp, long * offsetp);
-static const char *	getrule(const char * strp, struct rule * rulep);
-static void		gmtload(struct state * sp);
-static struct tm *	gmtsub(const time_t * timep, long offset,
-				struct tm * tmp);
-static struct tm *	localsub(const time_t * timep, long offset,
-				struct tm * tmp);
-static int		increment_overflow(int * number, int delta);
-static int		leaps_thru_end_of(int y) ATTRIBUTE_PURE;
-static int		long_increment_overflow(long * number, int delta);
-static int		long_normalize_overflow(long * tensptr,
-				int * unitsptr, int base);
-static int		normalize_overflow(int * tensptr, int * unitsptr,
-				int base);
-static void		settzname(void);
-static time_t		time1(struct tm * tmp,
-				struct tm * (*funcp)(const time_t *,
-				long, struct tm *),
-				long offset);
-static time_t		time2(struct tm *tmp,
-				struct tm * (*funcp)(const time_t *,
-				long, struct tm*),
-				long offset, int * okayp);
-static time_t		time2sub(struct tm *tmp,
-				struct tm * (*funcp)(const time_t *,
-				long, struct tm*),
-				long offset, int * okayp, int do_norm_secs);
-static struct tm *	timesub(const time_t * timep, long offset,
-				const struct state * sp, struct tm * tmp);
-static int		tmcomp(const struct tm * atmp,
-				const struct tm * btmp);
-static time_t		transtime(time_t janfirst, int year,
-				  const struct rule * rulep, long offset)
-  ATTRIBUTE_PURE;
-static int		typesequiv(const struct state * sp, int a, int b);
-static int		tzload(const char * name, struct state * sp,
-				int doextend);
-static int		tzparse(const char * name, struct state * sp,
-				int lastditch);
-
-#ifdef ALL_STATE
-static struct state *	lclptr;
-static struct state *	gmtptr;
-#endif /* defined ALL_STATE */
-
-#ifndef ALL_STATE
-static struct state	lclmem;
-static struct state	gmtmem;
-#define lclptr		(&lclmem)
-#define gmtptr		(&gmtmem)
-#endif /* State Farm */
-
-#ifndef TZ_STRLEN_MAX
-#define TZ_STRLEN_MAX 255
-#endif /* !defined TZ_STRLEN_MAX */
-
-static char		lcl_TZname[TZ_STRLEN_MAX + 1];
-static int		lcl_is_set;
-static pthread_once_t	gmt_once = PTHREAD_ONCE_INIT;
-static pthread_rwlock_t	lcl_rwlock = PTHREAD_RWLOCK_INITIALIZER;
-static pthread_once_t	gmtime_once = PTHREAD_ONCE_INIT;
-static pthread_key_t	gmtime_key;
-static int		gmtime_key_error;
-static pthread_once_t	localtime_once = PTHREAD_ONCE_INIT;
-static pthread_key_t	localtime_key;
-static int		localtime_key_error;
-
-char *			tzname[2] = {
-	wildabbr,
-	wildabbr
-};
-
-/*
-** Section 4.12.3 of X3.159-1989 requires that
-**	Except for the strftime function, these functions [asctime,
-**	ctime, gmtime, localtime] return values in one of two static
-**	objects: a broken-down time structure and an array of char.
-** Thanks to Paul Eggert for noting this.
-*/
-
-static struct tm	tm;
-
-#ifdef USG_COMPAT
-time_t			timezone = 0;
-int			daylight = 0;
-#endif /* defined USG_COMPAT */
-
-#ifdef ALTZONE
-time_t			altzone = 0;
-#endif /* defined ALTZONE */
-
-static long
-detzcode(const char *const codep)
-{
-	long	result;
-	int	i;
-
-	result = (codep[0] & 0x80) ? ~0L : 0;
-	for (i = 0; i < 4; ++i)
-		result = (result << 8) | (codep[i] & 0xff);
-	return result;
-}
-
-static time_t
-detzcode64(const char *const codep)
-{
-	register time_t	result;
-	register int	i;
-
-	result = (codep[0] & 0x80) ?  (~(int_fast64_t) 0) : 0;
-	for (i = 0; i < 8; ++i)
-		result = result * 256 + (codep[i] & 0xff);
-	return result;
-}
-
-static void
-settzname(void)
-{
-	struct state * 	sp = lclptr;
-	int			i;
-
-	tzname[0] = wildabbr;
-	tzname[1] = wildabbr;
-#ifdef USG_COMPAT
-	daylight = 0;
-	timezone = 0;
-#endif /* defined USG_COMPAT */
-#ifdef ALTZONE
-	altzone = 0;
-#endif /* defined ALTZONE */
-#ifdef ALL_STATE
-	if (sp == NULL) {
-		tzname[0] = tzname[1] = gmt;
-		return;
-	}
-#endif /* defined ALL_STATE */
-	/*
-	** And to get the latest zone names into tzname. . .
-	*/
-	for (i = 0; i < sp->typecnt; ++i) {
-		const struct ttinfo * const ttisp = &sp->ttis[sp->types[i]];
-
-		tzname[ttisp->tt_isdst] =
-			&sp->chars[ttisp->tt_abbrind];
-#ifdef USG_COMPAT
-		if (ttisp->tt_isdst)
-			daylight = 1;
-		if (!ttisp->tt_isdst)
-			timezone = -(ttisp->tt_gmtoff);
-#endif /* defined USG_COMPAT */
-#ifdef ALTZONE
-		if (ttisp->tt_isdst)
-			altzone = -(ttisp->tt_gmtoff);
-#endif /* defined ALTZONE */
-	}
-	/*
-	** Finally, scrub the abbreviations.
-	** First, replace bogus characters.
-	*/
-	for (i = 0; i < sp->charcnt; ++i)
-		if (strchr(TZ_ABBR_CHAR_SET, sp->chars[i]) == NULL)
-			sp->chars[i] = TZ_ABBR_ERR_CHAR;
-	/*
-	** Second, truncate long abbreviations.
-	*/
-	for (i = 0; i < sp->typecnt; ++i) {
-		register const struct ttinfo * const	ttisp = &sp->ttis[i];
-		register char *				cp = &sp->chars[ttisp->tt_abbrind];
-
-		if (strlen(cp) > TZ_ABBR_MAX_LEN &&
-			strcmp(cp, GRANDPARENTED) != 0)
-				*(cp + TZ_ABBR_MAX_LEN) = '\0';
-	}
-}
-
-#ifdef DETECT_TZ_CHANGES
-/*
- * Determine if there's a change in the timezone since the last time we checked.
- * Returns: -1 on error
- * 	     0 if the timezone has not changed
- *	     1 if the timezone has changed
- */
-static int
-change_in_tz(const char *name)
-{
-	static char old_name[PATH_MAX];
-	static struct stat old_sb;
-	struct stat sb;
-	int error;
-
-	error = stat(name, &sb);
-	if (error != 0)
-		return -1;
-
-	if (strcmp(name, old_name) != 0) {
-		strlcpy(old_name, name, sizeof(old_name));
-		old_sb = sb;
-		return 1;
-	}
-
-	if (sb.st_dev != old_sb.st_dev ||
-	    sb.st_ino != old_sb.st_ino ||
-	    sb.st_ctime != old_sb.st_ctime ||
-	    sb.st_mtime != old_sb.st_mtime) {
-		old_sb = sb;
-		return 1;
-	}
-
-	return 0;
-}
-#else /* !DETECT_TZ_CHANGES */
-#define	change_in_tz(X)	1
-#endif /* !DETECT_TZ_CHANGES */
-
-static int
-differ_by_repeat(const time_t t1, const time_t t0)
-{
-	int_fast64_t _t0 = t0;
-	int_fast64_t _t1 = t1;
-
-	if (TYPE_INTEGRAL(time_t) &&
-		TYPE_BIT(time_t) - TYPE_SIGNED(time_t) < SECSPERREPEAT_BITS)
-			return 0;
-	//turn ((int_fast64_t)(t1 - t0) == SECSPERREPEAT);
-	return _t1 - _t0 == SECSPERREPEAT;
-}
-
-static int
-tzload(name, sp, doextend)
-const char *		name;
-struct state * const	sp;
-register const int	doextend;
-{
-	const char *	p;
-	int		i;
-	int		fid;
-	int		stored;
-	int		nread;
-	int		res;
-	int		ret;
-	union {
-		struct tzhead	tzhead;
-		char		buf[2 * sizeof(struct tzhead) +
-					2 * sizeof *sp +
-					4 * TZ_MAX_TIMES];
-	} *u;
-
-	u = NULL;
-	res = -1;
-	sp->goback = sp->goahead = FALSE;
-
-	if (name != NULL && issetugid() != 0)
-		if ((name[0] == ':' && name[1] == '/') || 
-		    name[0] == '/' || strchr(name, '.'))
-			name = NULL;
-	if (name == NULL && (name = TZDEFAULT) == NULL)
-		return -1;
-	{
-		struct stat	stab;
-		/*
-		** Section 4.9.1 of the C standard says that
-		** "FILENAME_MAX expands to an integral constant expression
-		** that is the size needed for an array of char large enough
-		** to hold the longest file name string that the implementation
-		** guarantees can be opened."
-		*/
-		char		*fullname;
-
-		fullname = malloc(FILENAME_MAX + 1);
-		if (fullname == NULL)
-			goto out;
-
-		if (name[0] == ':')
-			++name;
-		if (name[0] != '/') {
-			if ((p = TZDIR) == NULL) {
-				free(fullname);
-				return -1;
-			}
-			if (strlen(p) + 1 + strlen(name) >= FILENAME_MAX) {
-				free(fullname);
-				return -1;
-			}
-			(void) strcpy(fullname, p);
-			(void) strcat(fullname, "/");
-			(void) strcat(fullname, name);
-			name = fullname;
-		}
-		if (doextend == TRUE) {
-			/*
-			 * Detect if the timezone file has changed.  Check
-			 * 'doextend' to ignore TZDEFRULES; the change_in_tz()
-			 * function can only keep state for a single file.
-			 */
-			ret = change_in_tz(name);
-			if (ret <= 0) {
-				/*
-				 * Returns -1 if there was an error,
-				 * and 0 if the timezone had not changed.
-				 */
-				free(fullname);
-				return ret;
-			}
-		}
-		if ((fid = _open(name, OPEN_MODE)) == -1) {
-			free(fullname);
-			return -1;
-		}
-		if ((_fstat(fid, &stab) < 0) || !S_ISREG(stab.st_mode)) {
-			free(fullname);
-			_close(fid);
-			return -1;
-		}
-		free(fullname);
-	}
-	u = malloc(sizeof(*u));
-	if (u == NULL)
-		goto out;
-	nread = _read(fid, u->buf, sizeof u->buf);
-	if (_close(fid) < 0 || nread <= 0)
-		goto out;
-	for (stored = 4; stored <= 8; stored *= 2) {
-		int		ttisstdcnt;
-		int		ttisgmtcnt;
-
-		ttisstdcnt = (int) detzcode(u->tzhead.tzh_ttisstdcnt);
-		ttisgmtcnt = (int) detzcode(u->tzhead.tzh_ttisgmtcnt);
-		sp->leapcnt = (int) detzcode(u->tzhead.tzh_leapcnt);
-		sp->timecnt = (int) detzcode(u->tzhead.tzh_timecnt);
-		sp->typecnt = (int) detzcode(u->tzhead.tzh_typecnt);
-		sp->charcnt = (int) detzcode(u->tzhead.tzh_charcnt);
-		p = u->tzhead.tzh_charcnt + sizeof u->tzhead.tzh_charcnt;
-		if (sp->leapcnt < 0 || sp->leapcnt > TZ_MAX_LEAPS ||
-			sp->typecnt <= 0 || sp->typecnt > TZ_MAX_TYPES ||
-			sp->timecnt < 0 || sp->timecnt > TZ_MAX_TIMES ||
-			sp->charcnt < 0 || sp->charcnt > TZ_MAX_CHARS ||
-			(ttisstdcnt != sp->typecnt && ttisstdcnt != 0) ||
-			(ttisgmtcnt != sp->typecnt && ttisgmtcnt != 0))
-				goto out;
-		if (nread - (p - u->buf) <
-			sp->timecnt * stored +		/* ats */
-			sp->timecnt +			/* types */
-			sp->typecnt * 6 +		/* ttinfos */
-			sp->charcnt +			/* chars */
-			sp->leapcnt * (stored + 4) +	/* lsinfos */
-			ttisstdcnt +			/* ttisstds */
-			ttisgmtcnt)			/* ttisgmts */
-				goto out;
-		for (i = 0; i < sp->timecnt; ++i) {
-			sp->ats[i] = (stored == 4) ?
-				detzcode(p) : detzcode64(p);
-			p += stored;
-		}
-		for (i = 0; i < sp->timecnt; ++i) {
-			sp->types[i] = (unsigned char) *p++;
-			if (sp->types[i] >= sp->typecnt)
-				goto out;
-		}
-		for (i = 0; i < sp->typecnt; ++i) {
-			struct ttinfo *	ttisp;
-
-			ttisp = &sp->ttis[i];
-			ttisp->tt_gmtoff = detzcode(p);
-			p += 4;
-			ttisp->tt_isdst = (unsigned char) *p++;
-			if (ttisp->tt_isdst != 0 && ttisp->tt_isdst != 1)
-				goto out;
-			ttisp->tt_abbrind = (unsigned char) *p++;
-			if (ttisp->tt_abbrind < 0 ||
-				ttisp->tt_abbrind > sp->charcnt)
-					goto out;
-		}
-		for (i = 0; i < sp->charcnt; ++i)
-			sp->chars[i] = *p++;
-		sp->chars[i] = '\0';	/* ensure '\0' at end */
-		for (i = 0; i < sp->leapcnt; ++i) {
-			struct lsinfo *	lsisp;
-
-			lsisp = &sp->lsis[i];
-			lsisp->ls_trans = (stored == 4) ?
-				detzcode(p) : detzcode64(p);
-			p += stored;
-			lsisp->ls_corr = detzcode(p);
-			p += 4;
-		}
-		for (i = 0; i < sp->typecnt; ++i) {
-			struct ttinfo *	ttisp;
-
-			ttisp = &sp->ttis[i];
-			if (ttisstdcnt == 0)
-				ttisp->tt_ttisstd = FALSE;
-			else {
-				ttisp->tt_ttisstd = *p++;
-				if (ttisp->tt_ttisstd != TRUE &&
-					ttisp->tt_ttisstd != FALSE)
-						goto out;
-			}
-		}
-		for (i = 0; i < sp->typecnt; ++i) {
-			struct ttinfo *	ttisp;
-
-			ttisp = &sp->ttis[i];
-			if (ttisgmtcnt == 0)
-				ttisp->tt_ttisgmt = FALSE;
-			else {
-				ttisp->tt_ttisgmt = *p++;
-				if (ttisp->tt_ttisgmt != TRUE &&
-					ttisp->tt_ttisgmt != FALSE)
-						goto out;
-			}
-		}
-		/*
-		** Out-of-sort ats should mean we're running on a
-		** signed time_t system but using a data file with
-		** unsigned values (or vice versa).
-		*/
-		for (i = 0; i < sp->timecnt - 2; ++i)
-			if (sp->ats[i] > sp->ats[i + 1]) {
-				++i;
-				if (TYPE_SIGNED(time_t)) {
-					/*
-					** Ignore the end (easy).
-					*/
-					sp->timecnt = i;
-				} else {
-					/*
-					** Ignore the beginning (harder).
-					*/
-					register int	j;
-
-					for (j = 0; j + i < sp->timecnt; ++j) {
-						sp->ats[j] = sp->ats[j + i];
-						sp->types[j] = sp->types[j + i];
-					}
-					sp->timecnt = j;
-				}
-				break;
-			}
-		/*
-		** If this is an old file, we're done.
-		*/
-		if (u->tzhead.tzh_version[0] == '\0')
-			break;
-		nread -= p - u->buf;
-		for (i = 0; i < nread; ++i)
-			u->buf[i] = p[i];
-		/*
-		** If this is a narrow integer time_t system, we're done.
-		*/
-		if (stored >= (int) sizeof(time_t) && TYPE_INTEGRAL(time_t))
-			break;
-	}
-	if (doextend && nread > 2 &&
-		u->buf[0] == '\n' && u->buf[nread - 1] == '\n' &&
-		sp->typecnt + 2 <= TZ_MAX_TYPES) {
-			struct state	*ts;
-			register int	result;
-
-			ts = malloc(sizeof(*ts));
-			if (ts == NULL)
-				goto out;
-			u->buf[nread - 1] = '\0';
-			result = tzparse(&u->buf[1], ts, FALSE);
-			if (result == 0 && ts->typecnt == 2 &&
-				sp->charcnt + ts->charcnt <= TZ_MAX_CHARS) {
-					for (i = 0; i < 2; ++i)
-						ts->ttis[i].tt_abbrind +=
-							sp->charcnt;
-					for (i = 0; i < ts->charcnt; ++i)
-						sp->chars[sp->charcnt++] =
-							ts->chars[i];
-					i = 0;
-					while (i < ts->timecnt &&
-						ts->ats[i] <=
-						sp->ats[sp->timecnt - 1])
-							++i;
-					while (i < ts->timecnt &&
-					    sp->timecnt < TZ_MAX_TIMES) {
-						sp->ats[sp->timecnt] =
-							ts->ats[i];
-						sp->types[sp->timecnt] =
-							sp->typecnt +
-							ts->types[i];
-						++sp->timecnt;
-						++i;
-					}
-					sp->ttis[sp->typecnt++] = ts->ttis[0];
-					sp->ttis[sp->typecnt++] = ts->ttis[1];
-			}
-			free(ts);
-	}
-	if (sp->timecnt > 1) {
-		for (i = 1; i < sp->timecnt; ++i)
-			if (typesequiv(sp, sp->types[i], sp->types[0]) &&
-				differ_by_repeat(sp->ats[i], sp->ats[0])) {
-					sp->goback = TRUE;
-					break;
-				}
-		for (i = sp->timecnt - 2; i >= 0; --i)
-			if (typesequiv(sp, sp->types[sp->timecnt - 1],
-				sp->types[i]) &&
-				differ_by_repeat(sp->ats[sp->timecnt - 1],
-				sp->ats[i])) {
-					sp->goahead = TRUE;
-					break;
-		}
-	}
-	res = 0;
-out:
-	free(u);
-	return (res);
-}
-
-static int
-typesequiv(sp, a, b)
-const struct state * const	sp;
-const int			a;
-const int			b;
-{
-	register int	result;
-
-	if (sp == NULL ||
-		a < 0 || a >= sp->typecnt ||
-		b < 0 || b >= sp->typecnt)
-			result = FALSE;
-	else {
-		register const struct ttinfo *	ap = &sp->ttis[a];
-		register const struct ttinfo *	bp = &sp->ttis[b];
-		result = ap->tt_gmtoff == bp->tt_gmtoff &&
-			ap->tt_isdst == bp->tt_isdst &&
-			ap->tt_ttisstd == bp->tt_ttisstd &&
-			ap->tt_ttisgmt == bp->tt_ttisgmt &&
-			strcmp(&sp->chars[ap->tt_abbrind],
-			&sp->chars[bp->tt_abbrind]) == 0;
-	}
-	return result;
-}
-
-static const int	mon_lengths[2][MONSPERYEAR] = {
-	{ 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 },
-	{ 31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 }
-};
-
-static const int	year_lengths[2] = {
-	DAYSPERNYEAR, DAYSPERLYEAR
-};
-
-/*
-** Given a pointer into a time zone string, scan until a character that is not
-** a valid character in a zone name is found. Return a pointer to that
-** character.
-*/
-
-static const char *
-getzname(strp)
-const char *	strp;
-{
-	char	c;
-
-	while ((c = *strp) != '\0' && !is_digit(c) && c != ',' && c != '-' &&
-		c != '+')
-			++strp;
-	return strp;
-}
-
-/*
-** Given a pointer into an extended time zone string, scan until the ending
-** delimiter of the zone name is located. Return a pointer to the delimiter.
-**
-** As with getzname above, the legal character set is actually quite
-** restricted, with other characters producing undefined results.
-** We don't do any checking here; checking is done later in common-case code.
-*/
-
-static const char *
-getqzname(register const char *strp, const int delim)
-{
-	register int	c;
-
-	while ((c = *strp) != '\0' && c != delim)
-		++strp;
-	return strp;
-}
-
-/*
-** Given a pointer into a time zone string, extract a number from that string.
-** Check that the number is within a specified range; if it is not, return
-** NULL.
-** Otherwise, return a pointer to the first character not part of the number.
-*/
-
-static const char *
-getnum(strp, nump, min, max)
-const char *	strp;
-int * const		nump;
-const int		min;
-const int		max;
-{
-	char	c;
-	int	num;
-
-	if (strp == NULL || !is_digit(c = *strp))
-		return NULL;
-	num = 0;
-	do {
-		num = num * 10 + (c - '0');
-		if (num > max)
-			return NULL;	/* illegal value */
-		c = *++strp;
-	} while (is_digit(c));
-	if (num < min)
-		return NULL;		/* illegal value */
-	*nump = num;
-	return strp;
-}
-
-/*
-** Given a pointer into a time zone string, extract a number of seconds,
-** in hh[:mm[:ss]] form, from the string.
-** If any error occurs, return NULL.
-** Otherwise, return a pointer to the first character not part of the number
-** of seconds.
-*/
-
-static const char *
-getsecs(strp, secsp)
-const char *	strp;
-long * const		secsp;
-{
-	int	num;
-
-	/*
-	** `HOURSPERDAY * DAYSPERWEEK - 1' allows quasi-Posix rules like
-	** "M10.4.6/26", which does not conform to Posix,
-	** but which specifies the equivalent of
-	** ``02:00 on the first Sunday on or after 23 Oct''.
-	*/
-	strp = getnum(strp, &num, 0, HOURSPERDAY * DAYSPERWEEK - 1);
-	if (strp == NULL)
-		return NULL;
-	*secsp = num * (long) SECSPERHOUR;
-	if (*strp == ':') {
-		++strp;
-		strp = getnum(strp, &num, 0, MINSPERHOUR - 1);
-		if (strp == NULL)
-			return NULL;
-		*secsp += num * SECSPERMIN;
-		if (*strp == ':') {
-			++strp;
-			/* `SECSPERMIN' allows for leap seconds. */
-			strp = getnum(strp, &num, 0, SECSPERMIN);
-			if (strp == NULL)
-				return NULL;
-			*secsp += num;
-		}
-	}
-	return strp;
-}
-
-/*
-** Given a pointer into a time zone string, extract an offset, in
-** [+-]hh[:mm[:ss]] form, from the string.
-** If any error occurs, return NULL.
-** Otherwise, return a pointer to the first character not part of the time.
-*/
-
-static const char *
-getoffset(strp, offsetp)
-const char *	strp;
-long * const		offsetp;
-{
-	int	neg = 0;
-
-	if (*strp == '-') {
-		neg = 1;
-		++strp;
-	} else if (*strp == '+')
-		++strp;
-	strp = getsecs(strp, offsetp);
-	if (strp == NULL)
-		return NULL;		/* illegal time */
-	if (neg)
-		*offsetp = -*offsetp;
-	return strp;
-}
-
-/*
-** Given a pointer into a time zone string, extract a rule in the form
-** date[/time]. See POSIX section 8 for the format of "date" and "time".
-** If a valid rule is not found, return NULL.
-** Otherwise, return a pointer to the first character not part of the rule.
-*/
-
-static const char *
-getrule(strp, rulep)
-const char *			strp;
-struct rule * const	rulep;
-{
-	if (*strp == 'J') {
-		/*
-		** Julian day.
-		*/
-		rulep->r_type = JULIAN_DAY;
-		++strp;
-		strp = getnum(strp, &rulep->r_day, 1, DAYSPERNYEAR);
-	} else if (*strp == 'M') {
-		/*
-		** Month, week, day.
-		*/
-		rulep->r_type = MONTH_NTH_DAY_OF_WEEK;
-		++strp;
-		strp = getnum(strp, &rulep->r_mon, 1, MONSPERYEAR);
-		if (strp == NULL)
-			return NULL;
-		if (*strp++ != '.')
-			return NULL;
-		strp = getnum(strp, &rulep->r_week, 1, 5);
-		if (strp == NULL)
-			return NULL;
-		if (*strp++ != '.')
-			return NULL;
-		strp = getnum(strp, &rulep->r_day, 0, DAYSPERWEEK - 1);
-	} else if (is_digit(*strp)) {
-		/*
-		** Day of year.
-		*/
-		rulep->r_type = DAY_OF_YEAR;
-		strp = getnum(strp, &rulep->r_day, 0, DAYSPERLYEAR - 1);
-	} else	return NULL;		/* invalid format */
-	if (strp == NULL)
-		return NULL;
-	if (*strp == '/') {
-		/*
-		** Time specified.
-		*/
-		++strp;
-		strp = getsecs(strp, &rulep->r_time);
-	} else	rulep->r_time = 2 * SECSPERHOUR;	/* default = 2:00:00 */
-	return strp;
-}
-
-/*
-** Given the Epoch-relative time of January 1, 00:00:00 UTC, in a year, the
-** year, a rule, and the offset from UTC at the time that rule takes effect,
-** calculate the Epoch-relative time that rule takes effect.
-*/
-
-static time_t
-transtime(janfirst, year, rulep, offset)
-const time_t				janfirst;
-const int				year;
-const struct rule * const	rulep;
-const long				offset;
-{
-	int	leapyear;
-	time_t	value;
-	int	i;
-	int		d, m1, yy0, yy1, yy2, dow;
-
-	INITIALIZE(value);
-	leapyear = isleap(year);
-	switch (rulep->r_type) {
-
-	case JULIAN_DAY:
-		/*
-		** Jn - Julian day, 1 == January 1, 60 == March 1 even in leap
-		** years.
-		** In non-leap years, or if the day number is 59 or less, just
-		** add SECSPERDAY times the day number-1 to the time of
-		** January 1, midnight, to get the day.
-		*/
-		value = janfirst + (rulep->r_day - 1) * SECSPERDAY;
-		if (leapyear && rulep->r_day >= 60)
-			value += SECSPERDAY;
-		break;
-
-	case DAY_OF_YEAR:
-		/*
-		** n - day of year.
-		** Just add SECSPERDAY times the day number to the time of
-		** January 1, midnight, to get the day.
-		*/
-		value = janfirst + rulep->r_day * SECSPERDAY;
-		break;
-
-	case MONTH_NTH_DAY_OF_WEEK:
-		/*
-		** Mm.n.d - nth "dth day" of month m.
-		*/
-		value = janfirst;
-		for (i = 0; i < rulep->r_mon - 1; ++i)
-			value += mon_lengths[leapyear][i] * SECSPERDAY;
-
-		/*
-		** Use Zeller's Congruence to get day-of-week of first day of
-		** month.
-		*/
-		m1 = (rulep->r_mon + 9) % 12 + 1;
-		yy0 = (rulep->r_mon <= 2) ? (year - 1) : year;
-		yy1 = yy0 / 100;
-		yy2 = yy0 % 100;
-		dow = ((26 * m1 - 2) / 10 +
-			1 + yy2 + yy2 / 4 + yy1 / 4 - 2 * yy1) % 7;
-		if (dow < 0)
-			dow += DAYSPERWEEK;
-
-		/*
-		** "dow" is the day-of-week of the first day of the month. Get
-		** the day-of-month (zero-origin) of the first "dow" day of the
-		** month.
-		*/
-		d = rulep->r_day - dow;
-		if (d < 0)
-			d += DAYSPERWEEK;
-		for (i = 1; i < rulep->r_week; ++i) {
-			if (d + DAYSPERWEEK >=
-				mon_lengths[leapyear][rulep->r_mon - 1])
-					break;
-			d += DAYSPERWEEK;
-		}
-
-		/*
-		** "d" is the day-of-month (zero-origin) of the day we want.
-		*/
-		value += d * SECSPERDAY;
-		break;
-	}
-
-	/*
-	** "value" is the Epoch-relative time of 00:00:00 UTC on the day in
-	** question. To get the Epoch-relative time of the specified local
-	** time on that day, add the transition time and the current offset
-	** from UTC.
-	*/
-	return value + rulep->r_time + offset;
-}
-
-/*
-** Given a POSIX section 8-style TZ string, fill in the rule tables as
-** appropriate.
-*/
-
-static int
-tzparse(name, sp, lastditch)
-const char *			name;
-struct state * const	sp;
-const int			lastditch;
-{
-	const char *			stdname;
-	const char *			dstname;
-	size_t				stdlen;
-	size_t				dstlen;
-	long				stdoffset;
-	long				dstoffset;
-	time_t *		atp;
-	unsigned char *	typep;
-	char *			cp;
-	int			load_result;
-
-	INITIALIZE(dstname);
-	stdname = name;
-	if (lastditch) {
-		stdlen = strlen(name);	/* length of standard zone name */
-		name += stdlen;
-		if (stdlen >= sizeof sp->chars)
-			stdlen = (sizeof sp->chars) - 1;
-		stdoffset = 0;
-	} else {
-		if (*name == '<') {
-			name++;
-			stdname = name;
-			name = getqzname(name, '>');
-			if (*name != '>')
-				return (-1);
-			stdlen = name - stdname;
-			name++;
-		} else {
-			name = getzname(name);
-			stdlen = name - stdname;
-		}
-		if (*name == '\0')
-			return -1;	/* was "stdoffset = 0;" */
-		else {
-			name = getoffset(name, &stdoffset);
-			if (name == NULL)
-				return -1;
-		}
-	}
-	load_result = tzload(TZDEFRULES, sp, FALSE);
-	if (load_result != 0)
-		sp->leapcnt = 0;		/* so, we're off a little */
-	if (*name != '\0') {
-		if (*name == '<') {
-			dstname = ++name;
-			name = getqzname(name, '>');
-			if (*name != '>')
-				return -1;
-			dstlen = name - dstname;
-			name++;
-		} else {
-			dstname = name;
-			name = getzname(name);
-			dstlen = name - dstname; /* length of DST zone name */
-		}
-		if (*name != '\0' && *name != ',' && *name != ';') {
-			name = getoffset(name, &dstoffset);
-			if (name == NULL)
-				return -1;
-		} else	dstoffset = stdoffset - SECSPERHOUR;
-		if (*name == '\0' && load_result != 0)
-			name = TZDEFRULESTRING;
-		if (*name == ',' || *name == ';') {
-			struct rule	start;
-			struct rule	end;
-			int	year;
-			time_t	janfirst;
-			time_t		starttime;
-			time_t		endtime;
-
-			++name;
-			if ((name = getrule(name, &start)) == NULL)
-				return -1;
-			if (*name++ != ',')
-				return -1;
-			if ((name = getrule(name, &end)) == NULL)
-				return -1;
-			if (*name != '\0')
-				return -1;
-			sp->typecnt = 2;	/* standard time and DST */
-			/*
-			** Two transitions per year, from EPOCH_YEAR forward.
-			*/
-			sp->ttis[0].tt_gmtoff = -dstoffset;
-			sp->ttis[0].tt_isdst = 1;
-			sp->ttis[0].tt_abbrind = stdlen + 1;
-			sp->ttis[1].tt_gmtoff = -stdoffset;
-			sp->ttis[1].tt_isdst = 0;
-			sp->ttis[1].tt_abbrind = 0;
-			atp = sp->ats;
-			typep = sp->types;
-			janfirst = 0;
-			sp->timecnt = 0;
-			for (year = EPOCH_YEAR;
-			    sp->timecnt + 2 <= TZ_MAX_TIMES;
-			    ++year) {
-			    	time_t	newfirst;
-
-				starttime = transtime(janfirst, year, &start,
-					stdoffset);
-				endtime = transtime(janfirst, year, &end,
-					dstoffset);
-				if (starttime > endtime) {
-					*atp++ = endtime;
-					*typep++ = 1;	/* DST ends */
-					*atp++ = starttime;
-					*typep++ = 0;	/* DST begins */
-				} else {
-					*atp++ = starttime;
-					*typep++ = 0;	/* DST begins */
-					*atp++ = endtime;
-					*typep++ = 1;	/* DST ends */
-				}
-				sp->timecnt += 2;
-				newfirst = janfirst;
-				newfirst += year_lengths[isleap(year)] *
-					SECSPERDAY;
-				if (newfirst <= janfirst)
-					break;
-				janfirst = newfirst;
-			}
-		} else {
-			long	theirstdoffset;
-			long	theirdstoffset;
-			long	theiroffset;
-			int	isdst;
-			int	i;
-			int	j;
-
-			if (*name != '\0')
-				return -1;
-			/*
-			** Initial values of theirstdoffset and theirdstoffset.
-			*/
-			theirstdoffset = 0;
-			for (i = 0; i < sp->timecnt; ++i) {
-				j = sp->types[i];
-				if (!sp->ttis[j].tt_isdst) {
-					theirstdoffset =
-						-sp->ttis[j].tt_gmtoff;
-					break;
-				}
-			}
-			theirdstoffset = 0;
-			for (i = 0; i < sp->timecnt; ++i) {
-				j = sp->types[i];
-				if (sp->ttis[j].tt_isdst) {
-					theirdstoffset =
-						-sp->ttis[j].tt_gmtoff;
-					break;
-				}
-			}
-			/*
-			** Initially we're assumed to be in standard time.
-			*/
-			isdst = FALSE;
-			theiroffset = theirstdoffset;
-			/*
-			** Now juggle transition times and types
-			** tracking offsets as you do.
-			*/
-			for (i = 0; i < sp->timecnt; ++i) {
-				j = sp->types[i];
-				sp->types[i] = sp->ttis[j].tt_isdst;
-				if (sp->ttis[j].tt_ttisgmt) {
-					/* No adjustment to transition time */
-				} else {
-					/*
-					** If summer time is in effect, and the
-					** transition time was not specified as
-					** standard time, add the summer time
-					** offset to the transition time;
-					** otherwise, add the standard time
-					** offset to the transition time.
-					*/
-					/*
-					** Transitions from DST to DDST
-					** will effectively disappear since
-					** POSIX provides for only one DST
-					** offset.
-					*/
-					if (isdst && !sp->ttis[j].tt_ttisstd) {
-						sp->ats[i] += dstoffset -
-							theirdstoffset;
-					} else {
-						sp->ats[i] += stdoffset -
-							theirstdoffset;
-					}
-				}
-				theiroffset = -sp->ttis[j].tt_gmtoff;
-				if (sp->ttis[j].tt_isdst)
-					theirdstoffset = theiroffset;
-				else	theirstdoffset = theiroffset;
-			}
-			/*
-			** Finally, fill in ttis.
-			** ttisstd and ttisgmt need not be handled.
-			*/
-			sp->ttis[0].tt_gmtoff = -stdoffset;
-			sp->ttis[0].tt_isdst = FALSE;
-			sp->ttis[0].tt_abbrind = 0;
-			sp->ttis[1].tt_gmtoff = -dstoffset;
-			sp->ttis[1].tt_isdst = TRUE;
-			sp->ttis[1].tt_abbrind = stdlen + 1;
-			sp->typecnt = 2;
-		}
-	} else {
-		dstlen = 0;
-		sp->typecnt = 1;		/* only standard time */
-		sp->timecnt = 0;
-		sp->ttis[0].tt_gmtoff = -stdoffset;
-		sp->ttis[0].tt_isdst = 0;
-		sp->ttis[0].tt_abbrind = 0;
-	}
-	sp->charcnt = stdlen + 1;
-	if (dstlen != 0)
-		sp->charcnt += dstlen + 1;
-	if ((size_t) sp->charcnt > sizeof sp->chars)
-		return -1;
-	cp = sp->chars;
-	(void) strncpy(cp, stdname, stdlen);
-	cp += stdlen;
-	*cp++ = '\0';
-	if (dstlen != 0) {
-		(void) strncpy(cp, dstname, dstlen);
-		*(cp + dstlen) = '\0';
-	}
-	return 0;
-}
-
-static void
-gmtload(struct state *const sp)
-{
-	if (tzload(gmt, sp, TRUE) != 0)
-		(void) tzparse(gmt, sp, TRUE);
-}
-
-#ifdef DETECT_TZ_CHANGES
-static int
-recheck_tzdata()
-{
-	static time_t last_checked;
-	struct timespec now;
-	time_t current_time;
-	int error;
-
-	/*
-	 * We want to recheck the timezone file every 61 sec.
-	 */
-	error = clock_gettime(CLOCK_MONOTONIC, &now);
-	if (error < 0) {
-		/* XXX: Can we somehow report this? */
-		return 0;
-	}
-
-	current_time = now.tv_sec;
-	if ((current_time - last_checked > 61) ||
-	    (last_checked > current_time)) {
-		last_checked = current_time;
-		return 1;
-	}
-
-	return 0;
-}
-#else /* !DETECT_TZ_CHANGES */
-#define	recheck_tzdata()	0
-#endif /* !DETECT_TZ_CHANGES */
-
-static void
-tzsetwall_basic(int rdlocked)
-{
-	if (!rdlocked)
-		_RWLOCK_RDLOCK(&lcl_rwlock);
-	if (lcl_is_set < 0 && recheck_tzdata() == 0) {
-		if (!rdlocked)
-			_RWLOCK_UNLOCK(&lcl_rwlock);
-		return;
-	}
-	_RWLOCK_UNLOCK(&lcl_rwlock);
-
-	_RWLOCK_WRLOCK(&lcl_rwlock);
-	lcl_is_set = -1;
-
-#ifdef ALL_STATE
-	if (lclptr == NULL) {
-		lclptr = calloc(1, sizeof *lclptr);
-		if (lclptr == NULL) {
-			settzname();	/* all we can do */
-			_RWLOCK_UNLOCK(&lcl_rwlock);
-			if (rdlocked)
-				_RWLOCK_RDLOCK(&lcl_rwlock);
-			return;
-		}
-	}
-#endif /* defined ALL_STATE */
-	if (tzload((char *) NULL, lclptr, TRUE) != 0)
-		gmtload(lclptr);
-	settzname();
-	_RWLOCK_UNLOCK(&lcl_rwlock);
-
-	if (rdlocked)
-		_RWLOCK_RDLOCK(&lcl_rwlock);
-}
-
-void
-tzsetwall(void)
-{
-	tzsetwall_basic(0);
-}
-
-static void
-tzset_basic(int rdlocked)
-{
-	const char *	name;
-
-	name = getenv("TZ");
-	if (name == NULL) {
-		tzsetwall_basic(rdlocked);
-		return;
-	}
-
-	if (!rdlocked)
-		_RWLOCK_RDLOCK(&lcl_rwlock);
-	if (lcl_is_set > 0 && strcmp(lcl_TZname, name) == 0) {
-		if (!rdlocked)
-			_RWLOCK_UNLOCK(&lcl_rwlock);
-		return;
-	}
-	_RWLOCK_UNLOCK(&lcl_rwlock);
-
-	_RWLOCK_WRLOCK(&lcl_rwlock);
-	lcl_is_set = strlen(name) < sizeof lcl_TZname;
-	if (lcl_is_set)
-		(void) strcpy(lcl_TZname, name);
-
-#ifdef ALL_STATE
-	if (lclptr == NULL) {
-		lclptr = (struct state *) calloc(1, sizeof *lclptr);
-		if (lclptr == NULL) {
-			settzname();	/* all we can do */
-			_RWLOCK_UNLOCK(&lcl_rwlock);
-			if (rdlocked)
-				_RWLOCK_RDLOCK(&lcl_rwlock);
-			return;
-		}
-	}
-#endif /* defined ALL_STATE */
-	if (*name == '\0') {
-		/*
-		** User wants it fast rather than right.
-		*/
-		lclptr->leapcnt = 0;		/* so, we're off a little */
-		lclptr->timecnt = 0;
-		lclptr->typecnt = 0;
-		lclptr->ttis[0].tt_isdst = 0;
-		lclptr->ttis[0].tt_gmtoff = 0;
-		lclptr->ttis[0].tt_abbrind = 0;
-		(void) strcpy(lclptr->chars, gmt);
-	} else if (tzload(name, lclptr, TRUE) != 0)
-		if (name[0] == ':' || tzparse(name, lclptr, FALSE) != 0)
-			(void) gmtload(lclptr);
-	settzname();
-	_RWLOCK_UNLOCK(&lcl_rwlock);
-
-	if (rdlocked)
-		_RWLOCK_RDLOCK(&lcl_rwlock);
-}
-
-void
-tzset(void)
-{
-	tzset_basic(0);
-}
-
-/*
-** The easy way to behave "as if no library function calls" localtime
-** is to not call it--so we drop its guts into "localsub", which can be
-** freely called. (And no, the PANS doesn't require the above behavior--
-** but it *is* desirable.)
-**
-** The unused offset argument is for the benefit of mktime variants.
-*/
-
-/*ARGSUSED*/
-static struct tm *
-localsub(const time_t *const timep, const long offset, struct tm *const tmp)
-{
-	struct state *		sp;
-	const struct ttinfo *	ttisp;
-	int			i;
-	struct tm *		result;
-	const time_t		t = *timep;
-
-	sp = lclptr;
-#ifdef ALL_STATE
-	if (sp == NULL)
-		return gmtsub(timep, offset, tmp);
-#endif /* defined ALL_STATE */
-	if ((sp->goback && t < sp->ats[0]) ||
-		(sp->goahead && t > sp->ats[sp->timecnt - 1])) {
-			time_t			newt = t;
-			register time_t		seconds;
-			register time_t		tcycles;
-			register int_fast64_t	icycles;
-
-			if (t < sp->ats[0])
-				seconds = sp->ats[0] - t;
-			else	seconds = t - sp->ats[sp->timecnt - 1];
-			--seconds;
-			tcycles = seconds / YEARSPERREPEAT / AVGSECSPERYEAR;
-			++tcycles;
-			icycles = tcycles;
-			if (tcycles - icycles >= 1 || icycles - tcycles >= 1)
-				return NULL;
-			seconds = icycles;
-			seconds *= YEARSPERREPEAT;
-			seconds *= AVGSECSPERYEAR;
-			if (t < sp->ats[0])
-				newt += seconds;
-			else	newt -= seconds;
-			if (newt < sp->ats[0] ||
-				newt > sp->ats[sp->timecnt - 1])
-					return NULL;	/* "cannot happen" */
-			result = localsub(&newt, offset, tmp);
-			if (result == tmp) {
-				register time_t	newy;
-
-				newy = tmp->tm_year;
-				if (t < sp->ats[0])
-					newy -= icycles * YEARSPERREPEAT;
-				else	newy += icycles * YEARSPERREPEAT;
-				tmp->tm_year = newy;
-				if (tmp->tm_year != newy)
-					return NULL;
-			}
-			return result;
-	}
-	if (sp->timecnt == 0 || t < sp->ats[0]) {
-		i = 0;
-		while (sp->ttis[i].tt_isdst)
-			if (++i >= sp->typecnt) {
-				i = 0;
-				break;
-			}
-	} else {
-		register int	lo = 1;
-		register int	hi = sp->timecnt;
-
-		while (lo < hi) {
-			register int	mid = (lo + hi) >> 1;
-
-			if (t < sp->ats[mid])
-				hi = mid;
-			else	lo = mid + 1;
-		}
-		i = (int) sp->types[lo - 1];
-	}
-	ttisp = &sp->ttis[i];
-	/*
-	** To get (wrong) behavior that's compatible with System V Release 2.0
-	** you'd replace the statement below with
-	**	t += ttisp->tt_gmtoff;
-	**	timesub(&t, 0L, sp, tmp);
-	*/
-	result = timesub(&t, ttisp->tt_gmtoff, sp, tmp);
-	tmp->tm_isdst = ttisp->tt_isdst;
-	tzname[tmp->tm_isdst] = &sp->chars[ttisp->tt_abbrind];
-#ifdef TM_ZONE
-	tmp->TM_ZONE = &sp->chars[ttisp->tt_abbrind];
-#endif /* defined TM_ZONE */
-	return result;
-}
-
-static void
-localtime_key_init(void)
-{
-
-	localtime_key_error = _pthread_key_create(&localtime_key, free);
-}
-
-struct tm *
-localtime(const time_t *const timep)
-{
-	struct tm *p_tm;
-
-	if (__isthreaded != 0) {
-		_pthread_once(&localtime_once, localtime_key_init);
-		if (localtime_key_error != 0) {
-			errno = localtime_key_error;
-			return(NULL);
-		}
-		p_tm = _pthread_getspecific(localtime_key);
-		if (p_tm == NULL) {
-			if ((p_tm = (struct tm *)malloc(sizeof(struct tm)))
-			    == NULL)
-				return(NULL);
-			_pthread_setspecific(localtime_key, p_tm);
-		}
-		_RWLOCK_RDLOCK(&lcl_rwlock);
-		tzset_basic(1);
-		p_tm = localsub(timep, 0L, p_tm);
-		_RWLOCK_UNLOCK(&lcl_rwlock);
-	} else {
-		tzset_basic(0);
-		p_tm = localsub(timep, 0L, &tm);
-	}
-	return(p_tm);
-}
-
-/*
-** Re-entrant version of localtime.
-*/
-
-struct tm *
-localtime_r(const time_t *const timep, struct tm *tmp)
-{
-	_RWLOCK_RDLOCK(&lcl_rwlock);
-	tzset_basic(1);
-	tmp = localsub(timep, 0L, tmp);
-	_RWLOCK_UNLOCK(&lcl_rwlock);
-	return tmp;
-}
-
-static void
-gmt_init(void)
-{
-
-#ifdef ALL_STATE
-	gmtptr = (struct state *) calloc(1, sizeof *gmtptr);
-	if (gmtptr != NULL)
-#endif /* defined ALL_STATE */
-		gmtload(gmtptr);
-}
-
-/*
-** gmtsub is to gmtime as localsub is to localtime.
-*/
-
-static struct tm *
-gmtsub(timep, offset, tmp)
-const time_t * const	timep;
-const long		offset;
-struct tm * const	tmp;
-{
-	register struct tm *	result;
-
-	_once(&gmt_once, gmt_init);
-	result = timesub(timep, offset, gmtptr, tmp);
-#ifdef TM_ZONE
-	/*
-	** Could get fancy here and deliver something such as
-	** "UTC+xxxx" or "UTC-xxxx" if offset is non-zero,
-	** but this is no time for a treasure hunt.
-	*/
-	if (offset != 0)
-		tmp->TM_ZONE = wildabbr;
-	else {
-#ifdef ALL_STATE
-		if (gmtptr == NULL)
-			tmp->TM_ZONE = gmt;
-		else	tmp->TM_ZONE = gmtptr->chars;
-#endif /* defined ALL_STATE */
-#ifndef ALL_STATE
-		tmp->TM_ZONE = gmtptr->chars;
-#endif /* State Farm */
-	}
-#endif /* defined TM_ZONE */
-	return result;
-}
-
-static void
-gmtime_key_init(void)
-{
-
-	gmtime_key_error = _pthread_key_create(&gmtime_key, free);
-}
-
-struct tm *
-gmtime(const time_t *const timep)
-{
-	struct tm *p_tm;
-
-	if (__isthreaded != 0) {
-		_pthread_once(&gmtime_once, gmtime_key_init);
-		if (gmtime_key_error != 0) {
-			errno = gmtime_key_error;
-			return(NULL);
-		}
-		/*
-		 * Changed to follow POSIX.1 threads standard, which
-		 * is what BSD currently has.
-		 */
-		if ((p_tm = _pthread_getspecific(gmtime_key)) == NULL) {
-			if ((p_tm = (struct tm *)malloc(sizeof(struct tm)))
-			    == NULL) {
-				return(NULL);
-			}
-			_pthread_setspecific(gmtime_key, p_tm);
-		}
-		gmtsub(timep, 0L, p_tm);
-		return(p_tm);
-	}
-	else {
-		gmtsub(timep, 0L, &tm);
-		return(&tm);
-	}
-}
-
-/*
-* Re-entrant version of gmtime.
-*/
-
-struct tm *
-gmtime_r(const time_t *const timep, struct tm *tmp)
-{
-	return gmtsub(timep, 0L, tmp);
-}
-
-#ifdef STD_INSPIRED
-
-struct tm *
-offtime(const time_t *const timep, const long offset)
-{
-	return gmtsub(timep, offset, &tm);
-}
-
-#endif /* defined STD_INSPIRED */
-
-/*
-** Return the number of leap years through the end of the given year
-** where, to make the math easy, the answer for year zero is defined as zero.
-*/
-
-static int
-leaps_thru_end_of(y)
-register const int	y;
-{
-	return (y >= 0) ? (y / 4 - y / 100 + y / 400) :
-		-(leaps_thru_end_of(-(y + 1)) + 1);
-}
-
-static struct tm *
-timesub(timep, offset, sp, tmp)
-const time_t * const			timep;
-const long				offset;
-const struct state * const	sp;
-struct tm * const		tmp;
-{
-	const struct lsinfo *	lp;
-	time_t			tdays;
-	int			idays;	/* unsigned would be so 2003 */
-	long			rem;
-	int			y;
-	const int *		ip;
-	long			corr;
-	int			hit;
-	int			i;
-
-	corr = 0;
-	hit = 0;
-#ifdef ALL_STATE
-	i = (sp == NULL) ? 0 : sp->leapcnt;
-#endif /* defined ALL_STATE */
-#ifndef ALL_STATE
-	i = sp->leapcnt;
-#endif /* State Farm */
-	while (--i >= 0) {
-		lp = &sp->lsis[i];
-		if (*timep >= lp->ls_trans) {
-			if (*timep == lp->ls_trans) {
-				hit = ((i == 0 && lp->ls_corr > 0) ||
-					lp->ls_corr > sp->lsis[i - 1].ls_corr);
-				if (hit)
-					while (i > 0 &&
-						sp->lsis[i].ls_trans ==
-						sp->lsis[i - 1].ls_trans + 1 &&
-						sp->lsis[i].ls_corr ==
-						sp->lsis[i - 1].ls_corr + 1) {
-							++hit;
-							--i;
-					}
-			}
-			corr = lp->ls_corr;
-			break;
-		}
-	}
-	y = EPOCH_YEAR;
-	tdays = *timep / SECSPERDAY;
-	rem = *timep - tdays * SECSPERDAY;
-	while (tdays < 0 || tdays >= year_lengths[isleap(y)]) {
-		int		newy;
-		register time_t	tdelta;
-		register int	idelta;
-		register int	leapdays;
-
-		tdelta = tdays / DAYSPERLYEAR;
-		idelta = tdelta;
-		if (tdelta - idelta >= 1 || idelta - tdelta >= 1)
-			return NULL;
-		if (idelta == 0)
-			idelta = (tdays < 0) ? -1 : 1;
-		newy = y;
-		if (increment_overflow(&newy, idelta))
-			return NULL;
-		leapdays = leaps_thru_end_of(newy - 1) -
-			leaps_thru_end_of(y - 1);
-		tdays -= ((time_t) newy - y) * DAYSPERNYEAR;
-		tdays -= leapdays;
-		y = newy;
-	}
-	{
-		register long	seconds;
-
-		seconds = tdays * SECSPERDAY + 0.5;
-		tdays = seconds / SECSPERDAY;
-		rem += seconds - tdays * SECSPERDAY;
-	}
-	/*
-	** Given the range, we can now fearlessly cast...
-	*/
-	idays = tdays;
-	rem += offset - corr;
-	while (rem < 0) {
-		rem += SECSPERDAY;
-		--idays;
-	}
-	while (rem >= SECSPERDAY) {
-		rem -= SECSPERDAY;
-		++idays;
-	}
-	while (idays < 0) {
-		if (increment_overflow(&y, -1))
-			return NULL;
-		idays += year_lengths[isleap(y)];
-	}
-	while (idays >= year_lengths[isleap(y)]) {
-		idays -= year_lengths[isleap(y)];
-		if (increment_overflow(&y, 1))
-			return NULL;
-	}
-	tmp->tm_year = y;
-	if (increment_overflow(&tmp->tm_year, -TM_YEAR_BASE))
-		return NULL;
-	tmp->tm_yday = idays;
-	/*
-	** The "extra" mods below avoid overflow problems.
-	*/
-	tmp->tm_wday = EPOCH_WDAY +
-		((y - EPOCH_YEAR) % DAYSPERWEEK) *
-		(DAYSPERNYEAR % DAYSPERWEEK) +
-		leaps_thru_end_of(y - 1) -
-		leaps_thru_end_of(EPOCH_YEAR - 1) +
-		idays;
-	tmp->tm_wday %= DAYSPERWEEK;
-	if (tmp->tm_wday < 0)
-		tmp->tm_wday += DAYSPERWEEK;
-	tmp->tm_hour = (int) (rem / SECSPERHOUR);
-	rem %= SECSPERHOUR;
-	tmp->tm_min = (int) (rem / SECSPERMIN);
-	/*
-	** A positive leap second requires a special
-	** representation. This uses "... ??:59:60" et seq.
-	*/
-	tmp->tm_sec = (int) (rem % SECSPERMIN) + hit;
-	ip = mon_lengths[isleap(y)];
-	for (tmp->tm_mon = 0; idays >= ip[tmp->tm_mon]; ++(tmp->tm_mon))
-		idays -= ip[tmp->tm_mon];
-	tmp->tm_mday = (int) (idays + 1);
-	tmp->tm_isdst = 0;
-#ifdef TM_GMTOFF
-	tmp->TM_GMTOFF = offset;
-#endif /* defined TM_GMTOFF */
-	return tmp;
-}
-
-char *
-ctime(const time_t *const timep)
-{
-/*
-** Section 4.12.3.2 of X3.159-1989 requires that
-**	The ctime function converts the calendar time pointed to by timer
-**	to local time in the form of a string. It is equivalent to
-**		asctime(localtime(timer))
-*/
-	return asctime(localtime(timep));
-}
-
-char *
-ctime_r(const time_t *const timep, char *buf)
-{
-	struct tm	mytm;
-
-	return asctime_r(localtime_r(timep, &mytm), buf);
-}
-
-/*
-** Adapted from code provided by Robert Elz, who writes:
-**	The "best" way to do mktime I think is based on an idea of Bob
-**	Kridle's (so its said...) from a long time ago.
-**	It does a binary search of the time_t space. Since time_t's are
-**	just 32 bits, its a max of 32 iterations (even at 64 bits it
-**	would still be very reasonable).
-*/
-
-#ifndef WRONG
-#define WRONG	(-1)
-#endif /* !defined WRONG */
-
-/*
-** Simplified normalize logic courtesy Paul Eggert.
-*/
-
-static int
-increment_overflow(number, delta)
-int *	number;
-int	delta;
-{
-	int	number0;
-
-	number0 = *number;
-	*number += delta;
-	return (*number < number0) != (delta < 0);
-}
-
-static int
-long_increment_overflow(number, delta)
-long *	number;
-int	delta;
-{
-	long	number0;
-
-	number0 = *number;
-	*number += delta;
-	return (*number < number0) != (delta < 0);
-}
-
-static int
-normalize_overflow(int *const tensptr, int *const unitsptr, const int base)
-{
-	int	tensdelta;
-
-	tensdelta = (*unitsptr >= 0) ?
-		(*unitsptr / base) :
-		(-1 - (-1 - *unitsptr) / base);
-	*unitsptr -= tensdelta * base;
-	return increment_overflow(tensptr, tensdelta);
-}
-
-static int
-long_normalize_overflow(long *const tensptr, int *const unitsptr, const int base)
-{
-	register int	tensdelta;
-
-	tensdelta = (*unitsptr >= 0) ?
-		(*unitsptr / base) :
-		(-1 - (-1 - *unitsptr) / base);
-	*unitsptr -= tensdelta * base;
-	return long_increment_overflow(tensptr, tensdelta);
-}
-
-static int
-tmcomp(atmp, btmp)
-const struct tm * const atmp;
-const struct tm * const btmp;
-{
-	int	result;
-
-	if ((result = (atmp->tm_year - btmp->tm_year)) == 0 &&
-		(result = (atmp->tm_mon - btmp->tm_mon)) == 0 &&
-		(result = (atmp->tm_mday - btmp->tm_mday)) == 0 &&
-		(result = (atmp->tm_hour - btmp->tm_hour)) == 0 &&
-		(result = (atmp->tm_min - btmp->tm_min)) == 0)
-			result = atmp->tm_sec - btmp->tm_sec;
-	return result;
-}
-
-static time_t
-time2sub(struct tm *const tmp,
-	 struct tm *(*const funcp)(const time_t *, long, struct tm *),
-	 const long offset,
-	 int *const okayp,
-	 const int do_norm_secs)
-{
-	const struct state *	sp;
-	int			dir;
-	int			i, j;
-	int			saved_seconds;
-	long			li;
-	time_t			lo;
-	time_t			hi;
-	long			y;
-	time_t			newt;
-	time_t			t;
-	struct tm		yourtm, mytm;
-
-	*okayp = FALSE;
-	yourtm = *tmp;
-	if (do_norm_secs) {
-		if (normalize_overflow(&yourtm.tm_min, &yourtm.tm_sec,
-			SECSPERMIN))
-				return WRONG;
-	}
-	if (normalize_overflow(&yourtm.tm_hour, &yourtm.tm_min, MINSPERHOUR))
-		return WRONG;
-	if (normalize_overflow(&yourtm.tm_mday, &yourtm.tm_hour, HOURSPERDAY))
-		return WRONG;
-	y = yourtm.tm_year;
-	if (long_normalize_overflow(&y, &yourtm.tm_mon, MONSPERYEAR))
-		return WRONG;
-	/*
-	** Turn y into an actual year number for now.
-	** It is converted back to an offset from TM_YEAR_BASE later.
-	*/
-	if (long_increment_overflow(&y, TM_YEAR_BASE))
-		return WRONG;
-	while (yourtm.tm_mday <= 0) {
-		if (long_increment_overflow(&y, -1))
-			return WRONG;
-		li = y + (1 < yourtm.tm_mon);
-		yourtm.tm_mday += year_lengths[isleap(li)];
-	}
-	while (yourtm.tm_mday > DAYSPERLYEAR) {
-		li = y + (1 < yourtm.tm_mon);
-		yourtm.tm_mday -= year_lengths[isleap(li)];
-		if (long_increment_overflow(&y, 1))
-			return WRONG;
-	}
-	for ( ; ; ) {
-		i = mon_lengths[isleap(y)][yourtm.tm_mon];
-		if (yourtm.tm_mday <= i)
-			break;
-		yourtm.tm_mday -= i;
-		if (++yourtm.tm_mon >= MONSPERYEAR) {
-			yourtm.tm_mon = 0;
-			if (long_increment_overflow(&y, 1))
-				return WRONG;
-		}
-	}
-	if (long_increment_overflow(&y, -TM_YEAR_BASE))
-		return WRONG;
-	yourtm.tm_year = y;
-	if (yourtm.tm_year != y)
-		return WRONG;
-	/* Don't go below 1900 for POLA */
-	if (yourtm.tm_year < 0)
-		return WRONG;
-	if (yourtm.tm_sec >= 0 && yourtm.tm_sec < SECSPERMIN)
-		saved_seconds = 0;
-	else if (y + TM_YEAR_BASE < EPOCH_YEAR) {
-		/*
-		** We can't set tm_sec to 0, because that might push the
-		** time below the minimum representable time.
-		** Set tm_sec to 59 instead.
-		** This assumes that the minimum representable time is
-		** not in the same minute that a leap second was deleted from,
-		** which is a safer assumption than using 58 would be.
-		*/
-		if (increment_overflow(&yourtm.tm_sec, 1 - SECSPERMIN))
-			return WRONG;
-		saved_seconds = yourtm.tm_sec;
-		yourtm.tm_sec = SECSPERMIN - 1;
-	} else {
-		saved_seconds = yourtm.tm_sec;
-		yourtm.tm_sec = 0;
-	}
-	/*
-	** Do a binary search (this works whatever time_t's type is).
-	*/
-	if (!TYPE_SIGNED(time_t)) {
-		lo = 0;
-		hi = lo - 1;
-	} else if (!TYPE_INTEGRAL(time_t)) {
-		if (sizeof(time_t) > sizeof(float))
-			hi = (time_t) DBL_MAX;
-		else	hi = (time_t) FLT_MAX;
-		lo = -hi;
-	} else {
-		lo = 1;
-		for (i = 0; i < (int) TYPE_BIT(time_t) - 1; ++i)
-			lo *= 2;
-		hi = -(lo + 1);
-	}
-	for ( ; ; ) {
-		t = lo / 2 + hi / 2;
-		if (t < lo)
-			t = lo;
-		else if (t > hi)
-			t = hi;
-		if ((*funcp)(&t, offset, &mytm) == NULL) {
-			/*
-			** Assume that t is too extreme to be represented in
-			** a struct tm; arrange things so that it is less
-			** extreme on the next pass.
-			*/
-			dir = (t > 0) ? 1 : -1;
-		} else	dir = tmcomp(&mytm, &yourtm);
-		if (dir != 0) {
-			if (t == lo) {
-				++t;
-				if (t <= lo)
-					return WRONG;
-				++lo;
-			} else if (t == hi) {
-				--t;
-				if (t >= hi)
-					return WRONG;
-				--hi;
-			}
-			if (lo > hi)
-				return WRONG;
-			if (dir > 0)
-				hi = t;
-			else	lo = t;
-			continue;
-		}
-		if (yourtm.tm_isdst < 0 || mytm.tm_isdst == yourtm.tm_isdst)
-			break;
-		/*
-		** Right time, wrong type.
-		** Hunt for right time, right type.
-		** It's okay to guess wrong since the guess
-		** gets checked.
-		*/
-		sp = (const struct state *)
-			((funcp == localsub) ? lclptr : gmtptr);
-#ifdef ALL_STATE
-		if (sp == NULL)
-			return WRONG;
-#endif /* defined ALL_STATE */
-		for (i = sp->typecnt - 1; i >= 0; --i) {
-			if (sp->ttis[i].tt_isdst != yourtm.tm_isdst)
-				continue;
-			for (j = sp->typecnt - 1; j >= 0; --j) {
-				if (sp->ttis[j].tt_isdst == yourtm.tm_isdst)
-					continue;
-				newt = t + sp->ttis[j].tt_gmtoff -
-					sp->ttis[i].tt_gmtoff;
-				if ((*funcp)(&newt, offset, &mytm) == NULL)
-					continue;
-				if (tmcomp(&mytm, &yourtm) != 0)
-					continue;
-				if (mytm.tm_isdst != yourtm.tm_isdst)
-					continue;
-				/*
-				** We have a match.
-				*/
-				t = newt;
-				goto label;
-			}
-		}
-		return WRONG;
-	}
-label:
-	newt = t + saved_seconds;
-	if ((newt < t) != (saved_seconds < 0))
-		return WRONG;
-	t = newt;
-	if ((*funcp)(&t, offset, tmp))
-		*okayp = TRUE;
-	return t;
-}
-
-static time_t
-time2(struct tm * const	tmp,
-      struct tm * (*const funcp)(const time_t *, long, struct tm *),
-      const long offset,
-      int *const okayp)
-{
-	time_t	t;
-
-	/*
-	** First try without normalization of seconds
-	** (in case tm_sec contains a value associated with a leap second).
-	** If that fails, try with normalization of seconds.
-	*/
-	t = time2sub(tmp, funcp, offset, okayp, FALSE);
-	return *okayp ? t : time2sub(tmp, funcp, offset, okayp, TRUE);
-}
-
-static time_t
-time1(tmp, funcp, offset)
-struct tm * const	tmp;
-struct tm * (* const  funcp)(const time_t *, long, struct tm *);
-const long		offset;
-{
-	time_t			t;
-	const struct state *	sp;
-	int			samei, otheri;
-	int			sameind, otherind;
-	int			i;
-	int			nseen;
-	int				seen[TZ_MAX_TYPES];
-	int				types[TZ_MAX_TYPES];
-	int				okay;
-
-	if (tmp == NULL) {
-		errno = EINVAL;
-		return WRONG;
-	}
-
-	if (tmp->tm_isdst > 1)
-		tmp->tm_isdst = 1;
-	t = time2(tmp, funcp, offset, &okay);
-#ifdef PCTS
-	/*
-	** PCTS code courtesy Grant Sullivan.
-	*/
-	if (okay)
-		return t;
-	if (tmp->tm_isdst < 0)
-		tmp->tm_isdst = 0;	/* reset to std and try again */
-#endif /* defined PCTS */
-#ifndef PCTS
-	if (okay || tmp->tm_isdst < 0)
-		return t;
-#endif /* !defined PCTS */
-	/*
-	** We're supposed to assume that somebody took a time of one type
-	** and did some math on it that yielded a "struct tm" that's bad.
-	** We try to divine the type they started from and adjust to the
-	** type they need.
-	*/
-	sp = (const struct state *) ((funcp == localsub) ? lclptr : gmtptr);
-#ifdef ALL_STATE
-	if (sp == NULL)
-		return WRONG;
-#endif /* defined ALL_STATE */
-	for (i = 0; i < sp->typecnt; ++i)
-		seen[i] = FALSE;
-	nseen = 0;
-	for (i = sp->timecnt - 1; i >= 0; --i)
-		if (!seen[sp->types[i]]) {
-			seen[sp->types[i]] = TRUE;
-			types[nseen++] = sp->types[i];
-		}
-	for (sameind = 0; sameind < nseen; ++sameind) {
-		samei = types[sameind];
-		if (sp->ttis[samei].tt_isdst != tmp->tm_isdst)
-			continue;
-		for (otherind = 0; otherind < nseen; ++otherind) {
-			otheri = types[otherind];
-			if (sp->ttis[otheri].tt_isdst == tmp->tm_isdst)
-				continue;
-			tmp->tm_sec += sp->ttis[otheri].tt_gmtoff -
-					sp->ttis[samei].tt_gmtoff;
-			tmp->tm_isdst = !tmp->tm_isdst;
-			t = time2(tmp, funcp, offset, &okay);
-			if (okay)
-				return t;
-			tmp->tm_sec -= sp->ttis[otheri].tt_gmtoff -
-					sp->ttis[samei].tt_gmtoff;
-			tmp->tm_isdst = !tmp->tm_isdst;
-		}
-	}
-	return WRONG;
-}
-
-time_t
-mktime(struct tm *const tmp)
-{
-	time_t mktime_return_value;
-	_RWLOCK_RDLOCK(&lcl_rwlock);
-	tzset_basic(1);
-	mktime_return_value = time1(tmp, localsub, 0L);
-	_RWLOCK_UNLOCK(&lcl_rwlock);
-	return(mktime_return_value);
-}
-
-#ifdef STD_INSPIRED
-
-time_t
-timelocal(struct tm *const tmp)
-{
-	if (tmp != NULL)
-		tmp->tm_isdst = -1;	/* in case it wasn't initialized */
-	return mktime(tmp);
-}
-
-time_t
-timegm(struct tm *const tmp)
-{
-	if (tmp != NULL)
-		tmp->tm_isdst = 0;
-	return time1(tmp, gmtsub, 0L);
-}
-
-time_t
-timeoff(struct tm *const tmp, const long offset)
-{
-	if (tmp != NULL)
-		tmp->tm_isdst = 0;
-	return time1(tmp, gmtsub, offset);
-}
-
-#endif /* defined STD_INSPIRED */
-
-#ifdef CMUCS
-
-/*
-** The following is supplied for compatibility with
-** previous versions of the CMUCS runtime library.
-*/
-
-long
-gtime(struct tm *const tmp)
-{
-	const time_t	t = mktime(tmp);
-
-	if (t == WRONG)
-		return -1;
-	return t;
-}
-
-#endif /* defined CMUCS */
-
-/*
-** XXX--is the below the right way to conditionalize??
-*/
-
-#ifdef STD_INSPIRED
-
-/*
-** IEEE Std 1003.1-1988 (POSIX) legislates that 536457599
-** shall correspond to "Wed Dec 31 23:59:59 UTC 1986", which
-** is not the case if we are accounting for leap seconds.
-** So, we provide the following conversion routines for use
-** when exchanging timestamps with POSIX conforming systems.
-*/
-
-static long
-leapcorr(time_t *timep)
-{
-	struct state *		sp;
-	struct lsinfo *	lp;
-	int			i;
-
-	sp = lclptr;
-	i = sp->leapcnt;
-	while (--i >= 0) {
-		lp = &sp->lsis[i];
-		if (*timep >= lp->ls_trans)
-			return lp->ls_corr;
-	}
-	return 0;
-}
-
-time_t
-time2posix(time_t t)
-{
-	tzset();
-	return t - leapcorr(&t);
-}
-
-time_t
-posix2time(time_t t)
-{
-	time_t	x;
-	time_t	y;
-
-	tzset();
-	/*
-	** For a positive leap second hit, the result
-	** is not unique. For a negative leap second
-	** hit, the corresponding time doesn't exist,
-	** so we return an adjacent second.
-	*/
-	x = t + leapcorr(&t);
-	y = x - leapcorr(&x);
-	if (y < t) {
-		do {
-			x++;
-			y = x - leapcorr(&x);
-		} while (y < t);
-		if (t != y)
-			return x - 1;
-	} else if (y > t) {
-		do {
-			--x;
-			y = x - leapcorr(&x);
-		} while (y > t);
-		if (t != y)
-			return x + 1;
-	}
-	return x;
-}
-
-#endif /* defined STD_INSPIRED */
diff --git a/contrib/tzcode/stdtime/private.h b/contrib/tzcode/stdtime/private.h
deleted file mode 100644
index 8f8f725f8193..000000000000
--- a/contrib/tzcode/stdtime/private.h
+++ /dev/null
@@ -1,318 +0,0 @@
-#ifndef PRIVATE_H
-
-#define PRIVATE_H
-
-/*
-** This file is in the public domain, so clarified as of
-** 1996-06-05 by Arthur David Olson.
-**
-** $FreeBSD$
-*/
-
-/* Stuff moved from Makefile.inc to reduce clutter */
-#ifndef TM_GMTOFF
-#define TM_GMTOFF	tm_gmtoff
-#define TM_ZONE		tm_zone
-#define STD_INSPIRED	1
-#define PCTS		1
-#define HAVE_LONG_DOUBLE 1
-#define HAVE_STRERROR	1
-#define	HAVE_UNISTD_H	1
-#define	LOCALE_HOME	_PATH_LOCALE
-#define TZDIR		"/usr/share/zoneinfo"
-#endif /* ndef TM_GMTOFF */
-
-/*
-** This header is for use ONLY with the time conversion code.
-** There is no guarantee that it will remain unchanged,
-** or that it will remain at all.
-** Do NOT copy it to any system include directory.
-** Thank you!
-*/
-
-/*
-** ID
-*/
-
-#ifndef lint
-#ifndef NOID
-/*
-static char	privatehid[] = "@(#)private.h	8.6";
-*/
-#endif /* !defined NOID */
-#endif /* !defined lint */
-
-#define GRANDPARENTED	"Local time zone must be set--see zic manual page"
-
-/*
-** Defaults for preprocessor symbols.
-** You can override these in your C compiler options, e.g. `-DHAVE_ADJTIME=0'.
-*/
-
-#ifndef HAVE_ADJTIME
-#define HAVE_ADJTIME		1
-#endif /* !defined HAVE_ADJTIME */
-
-#ifndef HAVE_GETTEXT
-#define HAVE_GETTEXT		0
-#endif /* !defined HAVE_GETTEXT */
-
-#ifndef HAVE_INCOMPATIBLE_CTIME_R
-#define HAVE_INCOMPATIBLE_CTIME_R	0
-#endif /* !defined INCOMPATIBLE_CTIME_R */
-
-#ifndef HAVE_SETTIMEOFDAY
-#define HAVE_SETTIMEOFDAY	3
-#endif /* !defined HAVE_SETTIMEOFDAY */
-
-#ifndef HAVE_SYMLINK
-#define HAVE_SYMLINK		1
-#endif /* !defined HAVE_SYMLINK */
-
-#ifndef HAVE_SYS_STAT_H
-#define HAVE_SYS_STAT_H		1
-#endif /* !defined HAVE_SYS_STAT_H */
-
-#ifndef HAVE_SYS_WAIT_H
-#define HAVE_SYS_WAIT_H		1
-#endif /* !defined HAVE_SYS_WAIT_H */
-
-#ifndef HAVE_UNISTD_H
-#define HAVE_UNISTD_H		1
-#endif /* !defined HAVE_UNISTD_H */
-
-#ifndef HAVE_UTMPX_H
-#define HAVE_UTMPX_H		0
-#endif /* !defined HAVE_UTMPX_H */
-
-#ifndef LOCALE_HOME
-#define LOCALE_HOME		"/usr/lib/locale"
-#endif /* !defined LOCALE_HOME */
-
-#if HAVE_INCOMPATIBLE_CTIME_R
-#define asctime_r _incompatible_asctime_r
-#define ctime_r _incompatible_ctime_r
-#endif /* HAVE_INCOMPATIBLE_CTIME_R */
-
-/*
-** Nested includes
-*/
-
-#include "sys/types.h"	/* for time_t */
-#include "stdio.h"
-#include "errno.h"
-#include "string.h"
-#include "limits.h"	/* for CHAR_BIT et al. */
-#include "time.h"
-#include "stdlib.h"
-
-#if HAVE_GETTEXT
-#include "libintl.h"
-#endif /* HAVE_GETTEXT */
-
-#if HAVE_SYS_WAIT_H
-#include <sys/wait.h>	/* for WIFEXITED and WEXITSTATUS */
-#endif /* HAVE_SYS_WAIT_H */
-
-#ifndef WIFEXITED
-#define WIFEXITED(status)	(((status) & 0xff) == 0)
-#endif /* !defined WIFEXITED */
-#ifndef WEXITSTATUS
-#define WEXITSTATUS(status)	(((status) >> 8) & 0xff)
-#endif /* !defined WEXITSTATUS */
-
-#if HAVE_UNISTD_H
-#include "unistd.h"	/* for F_OK, R_OK, and other POSIX goodness */
-#endif /* HAVE_UNISTD_H */
-
-#if !(HAVE_UNISTD_H)
-#ifndef F_OK
-#define F_OK	0
-#endif /* !defined F_OK */
-#ifndef R_OK
-#define R_OK	4
-#endif /* !defined R_OK */
-#endif /* !(HAVE_UNISTD_H) */
-
-/* Unlike <ctype.h>'s isdigit, this also works if c < 0 | c > UCHAR_MAX. */
-#define is_digit(c) ((unsigned)(c) - '0' <= 9)
-
-/*
-** Define HAVE_STDINT_H's default value here, rather than at the
-** start, since __GLIBC__'s value depends on previously-included
-** files.
-** (glibc 2.1 and later have stdint.h, even with pre-C99 compilers.)
-*/
-#ifndef HAVE_STDINT_H
-#define HAVE_STDINT_H \
-	(199901 <= __STDC_VERSION__ || \
-	2 < (__GLIBC__ + (0 < __GLIBC_MINOR__)))
-#endif /* !defined HAVE_STDINT_H */
-
-#if HAVE_STDINT_H
-#include "stdint.h"
-#endif /* !HAVE_STDINT_H */
-
-#ifndef INT_FAST64_MAX
-/* Pre-C99 GCC compilers define __LONG_LONG_MAX__ instead of LLONG_MAX.  */
-#if defined LLONG_MAX || defined __LONG_LONG_MAX__
-typedef long long	int_fast64_t;
-#else /* ! (defined LLONG_MAX || defined __LONG_LONG_MAX__) */
-#if (LONG_MAX >> 31) < 0xffffffff
-Please use a compiler that supports a 64-bit integer type (or wider);
-you may need to compile with "-DHAVE_STDINT_H".
-#endif /* (LONG_MAX >> 31) < 0xffffffff */
-typedef long		int_fast64_t;
-#endif /* ! (defined LLONG_MAX || defined __LONG_LONG_MAX__) */
-#endif /* !defined INT_FAST64_MAX */
-
-#ifndef INT32_MAX
-#define INT32_MAX 0x7fffffff
-#endif /* !defined INT32_MAX */
-#ifndef INT32_MIN
-#define INT32_MIN (-1 - INT32_MAX)
-#endif /* !defined INT32_MIN */
-
-#if 2 < __GNUC__ || (__GNUC__ == 2 && 96 <= __GNUC_MINOR__)
-# define ATTRIBUTE_PURE __attribute__ ((__pure__))
-#else
-# define ATTRIBUTE_PURE /* empty */
-#endif
-
-/*
-** Workarounds for compilers/systems.
-*/
-
-/*
-** Some time.h implementations don't declare asctime_r.
-** Others might define it as a macro.
-** Fix the former without affecting the latter.
-*/
-
-#ifndef asctime_r
-extern char *	asctime_r(struct tm const *, char *);
-#endif
-
-/*
-** Private function declarations.
-*/
-
-char *		icatalloc(char * old, const char * new);
-char *		icpyalloc(const char * string);
-const char *	scheck(const char * string, const char * format);
-
-/*
-** Finally, some convenience items.
-*/
-
-#ifndef TRUE
-#define TRUE	1
-#endif /* !defined TRUE */
-
-#ifndef FALSE
-#define FALSE	0
-#endif /* !defined FALSE */
-
-#ifndef TYPE_BIT
-#define TYPE_BIT(type)	(sizeof (type) * CHAR_BIT)
-#endif /* !defined TYPE_BIT */
-
-#ifndef TYPE_SIGNED
-#define TYPE_SIGNED(type) (((type) -1) < 0)
-#endif /* !defined TYPE_SIGNED */
-
-/*
-** Since the definition of TYPE_INTEGRAL contains floating point numbers,
-** it cannot be used in preprocessor directives.
-*/
-
-#ifndef TYPE_INTEGRAL
-#define	TYPE_INTEGRAL(type) (((type) 0.5) != 0.5)
-#endif /* !defined TYPE_INTEGRAL */
-
-#ifndef INT_STRLEN_MAXIMUM
-/*
-** 302 / 1000 is log10(2.0) rounded up.
-** Subtract one for the sign bit if the type is signed;
-** add one for integer division truncation;
-** add one more for a minus sign if the type is signed.
-*/
-#define INT_STRLEN_MAXIMUM(type) \
-	((TYPE_BIT(type) - TYPE_SIGNED(type)) * 302 / 1000 + \
-	1 + TYPE_SIGNED(type))
-#endif /* !defined INT_STRLEN_MAXIMUM */
-
-/*
-** INITIALIZE(x)
-*/
-
-#ifndef GNUC_or_lint
-#ifdef lint
-#define GNUC_or_lint
-#endif /* defined lint */
-#ifndef lint
-#ifdef __GNUC__
-#define GNUC_or_lint
-#endif /* defined __GNUC__ */
-#endif /* !defined lint */
-#endif /* !defined GNUC_or_lint */
-
-#ifndef INITIALIZE
-#ifdef GNUC_or_lint
-#define INITIALIZE(x)	((x) = 0)
-#endif /* defined GNUC_or_lint */
-#ifndef GNUC_or_lint
-#define INITIALIZE(x)
-#endif /* !defined GNUC_or_lint */
-#endif /* !defined INITIALIZE */
-
-/*
-** For the benefit of GNU folk...
-** `_(MSGID)' uses the current locale's message library string for MSGID.
-** The default is to use gettext if available, and use MSGID otherwise.
-*/
-
-#ifndef _
-#if HAVE_GETTEXT
-#define _(msgid) gettext(msgid)
-#else /* !HAVE_GETTEXT */
-#define _(msgid) msgid
-#endif /* !HAVE_GETTEXT */
-#endif /* !defined _ */
-
-#ifndef TZ_DOMAIN
-#define TZ_DOMAIN "tz"
-#endif /* !defined TZ_DOMAIN */
-
-#if HAVE_INCOMPATIBLE_CTIME_R
-#undef asctime_r
-#undef ctime_r
-char *asctime_r(struct tm const *, char *);
-char *ctime_r(time_t const *, char *);
-#endif /* HAVE_INCOMPATIBLE_CTIME_R */
-  
-#ifndef YEARSPERREPEAT
-#define YEARSPERREPEAT		400	/* years before a Gregorian repeat */
-#endif /* !defined YEARSPERREPEAT */
-
-/*
-** The Gregorian year averages 365.2425 days, which is 31556952 seconds.
-*/
-
-#ifndef AVGSECSPERYEAR
-#define AVGSECSPERYEAR		31556952L
-#endif /* !defined AVGSECSPERYEAR */
-
-#ifndef SECSPERREPEAT
-#define SECSPERREPEAT		((int_fast64_t) YEARSPERREPEAT * (int_fast64_t) AVGSECSPERYEAR)
-#endif /* !defined SECSPERREPEAT */
-
-#ifndef SECSPERREPEAT_BITS
-#define SECSPERREPEAT_BITS	34	/* ceil(log2(SECSPERREPEAT)) */
-#endif /* !defined SECSPERREPEAT_BITS */
-
-/*
-** UNIX was a registered trademark of The Open Group in 2003.
-*/
-
-#endif /* !defined PRIVATE_H */
diff --git a/contrib/tzcode/stdtime/tzfile.5 b/contrib/tzcode/stdtime/tzfile.5
deleted file mode 100644
index 5e911a5ee5c1..000000000000
--- a/contrib/tzcode/stdtime/tzfile.5
+++ /dev/null
@@ -1,152 +0,0 @@
-.\" $FreeBSD$
-.Dd September 13, 1994
-.Dt TZFILE 5
-.Os
-.Sh NAME
-.Nm tzfile
-.Nd timezone information
-.Sh SYNOPSIS
-.Fd #include \&"/usr/src/contrib/tzcode/stdtime/tzfile.h\&"
-.Sh DESCRIPTION
-The time zone information files used by
-.Xr tzset 3
-begin with the magic characters
-.Dq Li TZif
-to identify them as
-time zone information files,
-followed by a character identifying the version of the file's format
-(as of 2005, either an ASCII NUL or a '2')
-followed by fifteen bytes containing zeroes reserved for future use,
-followed by four four-byte values
-written in a ``standard'' byte order
-(the high-order byte of the value is written first).
-These values are,
-in order:
-.Pp
-.Bl -tag -compact -width tzh_ttisstdcnt
-.It Va tzh_ttisgmtcnt
-The number of UTC/local indicators stored in the file.
-.It Va tzh_ttisstdcnt
-The number of standard/wall indicators stored in the file.
-.It Va tzh_leapcnt
-The number of leap seconds for which data is stored in the file.
-.It Va tzh_timecnt
-The number of ``transition times'' for which data is stored
-in the file.
-.It Va tzh_typecnt
-The number of ``local time types'' for which data is stored
-in the file (must not be zero).
-.It Va tzh_charcnt
-The number of characters of ``time zone abbreviation strings''
-stored in the file.
-.El
-.Pp
-The above header is followed by
-.Va tzh_timecnt
-four-byte values of type
-.Fa long ,
-sorted in ascending order.
-These values are written in ``standard'' byte order.
-Each is used as a transition time (as returned by
-.Xr time 3 )
-at which the rules for computing local time change.
-Next come
-.Va tzh_timecnt
-one-byte values of type
-.Fa "unsigned char" ;
-each one tells which of the different types of ``local time'' types
-described in the file is associated with the same-indexed transition time.
-These values serve as indices into an array of
-.Fa ttinfo
-structures (with
-.Fa tzh_typecnt
-entries) that appears next in the file;
-these structures are defined as follows:
-.Pp
-.Bd -literal -offset indent
-struct ttinfo {
-	long	tt_gmtoff;
-	int	tt_isdst;
-	unsigned int	tt_abbrind;
-};
-.Ed
-.Pp
-Each structure is written as a four-byte value for
-.Va tt_gmtoff
-of type
-.Fa long ,
-in a standard byte order, followed by a one-byte value for
-.Va tt_isdst
-and a one-byte value for
-.Va tt_abbrind .
-In each structure,
-.Va tt_gmtoff
-gives the number of seconds to be added to UTC,
-.Li tt_isdst
-tells whether
-.Li tm_isdst
-should be set by
-.Xr localtime 3
-and
-.Va tt_abbrind
-serves as an index into the array of time zone abbreviation characters
-that follow the
-.Li ttinfo
-structure(s) in the file.
-.Pp
-Then there are
-.Va tzh_leapcnt
-pairs of four-byte values, written in standard byte order;
-the first value of each pair gives the time
-(as returned by
-.Xr time 3 )
-at which a leap second occurs;
-the second gives the
-.Em total
-number of leap seconds to be applied after the given time.
-The pairs of values are sorted in ascending order by time.
-.Pp
-Then there are
-.Va tzh_ttisstdcnt
-standard/wall indicators, each stored as a one-byte value;
-they tell whether the transition times associated with local time types
-were specified as standard time or wall clock time,
-and are used when a time zone file is used in handling POSIX-style
-time zone environment variables.
-.Pp
-Finally there are
-.Va tzh_ttisgmtcnt
-UTC/local indicators, each stored as a one-byte value;
-they tell whether the transition times associated with local time types
-were specified as UTC or local time,
-and are used when a time zone file is used in handling POSIX-style
-time zone environment variables.
-.Pp
-.Nm localtime
-uses the first standard-time
-.Li ttinfo
-structure in the file
-(or simply the first
-.Li ttinfo
-structure in the absence of a standard-time structure)
-if either
-.Li tzh_timecnt
-is zero or the time argument is less than the first transition time recorded
-in the file.
-.Pp
-For version-2-format time zone files,
-the above header and data is followed by a second header and data,
-identical in format except that eight bytes are used for each
-transition time or leap second time.
-After the second header and data comes a newline-enclosed,
-POSIX-TZ-environment-variable-style string for use in handling instants
-after the last transition time stored in the file
-(with nothing between the newlines if there is no POSIX representation for
-such instants).
-.Sh SEE ALSO
-.Xr ctime 3 ,
-.Xr time2posix 3 ,
-.Xr zic 8
-.\" @(#)tzfile.5	8.3
-.\" This file is in the public domain, so clarified as of
-.\" 1996-06-05 by Arthur David Olson.
diff --git a/contrib/tzcode/stdtime/tzfile.h b/contrib/tzcode/stdtime/tzfile.h
deleted file mode 100644
index 85b945e6dd75..000000000000
--- a/contrib/tzcode/stdtime/tzfile.h
+++ /dev/null
@@ -1,184 +0,0 @@
-#ifndef TZFILE_H
-#define TZFILE_H
-
-
-/*
-** This file is in the public domain, so clarified as of
-** 1996-06-05 by Arthur David Olson.
-**
-** $FreeBSD$
-*/
-
-/*
-** This header is for use ONLY with the time conversion code.
-** There is no guarantee that it will remain unchanged,
-** or that it will remain at all.
-** Do NOT copy it to any system include directory.
-** Thank you!
-*/
-
-/*
-** ID
-*/
-
-#ifndef lint
-#ifndef NOID
-/*
-static char	tzfilehid[] = "@(#)tzfile.h	8.1";
-*/
-#endif /* !defined NOID */
-#endif /* !defined lint */
-
-/*
-** Information about time zone files.
-*/
-
-#ifndef TZDIR
-#define TZDIR	"/usr/share/zoneinfo" /* Time zone object file directory */
-#endif /* !defined TZDIR */
-
-#ifndef TZDEFAULT
-#define TZDEFAULT	"/etc/localtime"
-#endif /* !defined TZDEFAULT */
-
-#ifndef TZDEFRULES
-#define TZDEFRULES	"posixrules"
-#endif /* !defined TZDEFRULES */
-
-/*
-** Each file begins with. . .
-*/
-
-#define	TZ_MAGIC	"TZif"
-
-struct tzhead {
-	char	tzh_magic[4];		/* TZ_MAGIC */
-	char	tzh_version[1];		/* '\0' or '2' as of 2005 */
-	char	tzh_reserved[15];	/* reserved--must be zero */
-	char	tzh_ttisgmtcnt[4];	/* coded number of trans. time flags */
-	char	tzh_ttisstdcnt[4];	/* coded number of trans. time flags */
-	char	tzh_leapcnt[4];		/* coded number of leap seconds */
-	char	tzh_timecnt[4];		/* coded number of transition times */
-	char	tzh_typecnt[4];		/* coded number of local time types */
-	char	tzh_charcnt[4];		/* coded number of abbr. chars */
-};
-
-/*
-** . . .followed by. . .
-**
-**	tzh_timecnt (char [4])s		coded transition times a la time(2)
-**	tzh_timecnt (unsigned char)s	types of local time starting at above
-**	tzh_typecnt repetitions of
-**		one (char [4])		coded UTC offset in seconds
-**		one (unsigned char)	used to set tm_isdst
-**		one (unsigned char)	that's an abbreviation list index
-**	tzh_charcnt (char)s		'\0'-terminated zone abbreviations
-**	tzh_leapcnt repetitions of
-**		one (char [4])		coded leap second transition times
-**		one (char [4])		total correction after above
-**	tzh_ttisstdcnt (char)s		indexed by type; if TRUE, transition
-**					time is standard time, if FALSE,
-**					transition time is wall clock time
-**					if absent, transition times are
-**					assumed to be wall clock time
-**	tzh_ttisgmtcnt (char)s		indexed by type; if TRUE, transition
-**					time is UTC, if FALSE,
-**					transition time is local time
-**					if absent, transition times are
-**					assumed to be local time
-*/
-
-/*
-** If tzh_version is '2' or greater, the above is followed by a second instance
-** of tzhead and a second instance of the data in which each coded transition
-** time uses 8 rather than 4 chars,
-** then a POSIX-TZ-environment-variable-style string for use in handling
-** instants after the last transition time stored in the file
-** (with nothing between the newlines if there is no POSIX representation for
-** such instants).
-*/
-
-/*
-** In the current implementation, "tzset()" refuses to deal with files that
-** exceed any of the limits below.
-*/
-
-#ifndef TZ_MAX_TIMES
-#define TZ_MAX_TIMES	1200
-#endif /* !defined TZ_MAX_TIMES */
-
-#ifndef TZ_MAX_TYPES
-#ifndef NOSOLAR
-#define TZ_MAX_TYPES	256 /* Limited by what (unsigned char)'s can hold */
-#endif /* !defined NOSOLAR */
-#ifdef NOSOLAR
-/*
-** Must be at least 14 for Europe/Riga as of Jan 12 1995,
-** as noted by Earl Chew.
-*/
-#define TZ_MAX_TYPES	20	/* Maximum number of local time types */
-#endif /* !defined NOSOLAR */
-#endif /* !defined TZ_MAX_TYPES */
-
-#ifndef TZ_MAX_CHARS
-#define TZ_MAX_CHARS	50	/* Maximum number of abbreviation characters */
-				/* (limited by what unsigned chars can hold) */
-#endif /* !defined TZ_MAX_CHARS */
-
-#ifndef TZ_MAX_LEAPS
-#define TZ_MAX_LEAPS	50	/* Maximum number of leap second corrections */
-#endif /* !defined TZ_MAX_LEAPS */
-
-#define SECSPERMIN	60
-#define MINSPERHOUR	60
-#define HOURSPERDAY	24
-#define DAYSPERWEEK	7
-#define DAYSPERNYEAR	365
-#define DAYSPERLYEAR	366
-#define SECSPERHOUR	(SECSPERMIN * MINSPERHOUR)
-#define SECSPERDAY	((long) SECSPERHOUR * HOURSPERDAY)
-#define MONSPERYEAR	12
-
-#define TM_SUNDAY	0
-#define TM_MONDAY	1
-#define TM_TUESDAY	2
-#define TM_WEDNESDAY	3
-#define TM_THURSDAY	4
-#define TM_FRIDAY	5
-#define TM_SATURDAY	6
-
-#define TM_JANUARY	0
-#define TM_FEBRUARY	1
-#define TM_MARCH	2
-#define TM_APRIL	3
-#define TM_MAY		4
-#define TM_JUNE		5
-#define TM_JULY		6
-#define TM_AUGUST	7
-#define TM_SEPTEMBER	8
-#define TM_OCTOBER	9
-#define TM_NOVEMBER	10
-#define TM_DECEMBER	11
-
-#define TM_YEAR_BASE	1900
-
-#define EPOCH_YEAR	1970
-#define EPOCH_WDAY	TM_THURSDAY
-
-#define isleap(y) (((y) % 4) == 0 && (((y) % 100) != 0 || ((y) % 400) == 0))
-
-/*
-** Since everything in isleap is modulo 400 (or a factor of 400), we know that
-**	isleap(y) == isleap(y % 400)
-** and so
-**	isleap(a + b) == isleap((a + b) % 400)
-** or
-**	isleap(a + b) == isleap(a % 400 + b % 400)
-** This is true even if % means modulo rather than Fortran remainder
-** (which is allowed by C89 but not C99).
-** We use this to avoid addition overflow problems.
-*/
-
-#define isleap_sum(a, b)	isleap((a) % 400 + (b) % 400)
-
-#endif /* !defined TZFILE_H */
diff --git a/contrib/tzcode/strftime.c b/contrib/tzcode/strftime.c
new file mode 100644
index 000000000000..b23b6101b150
--- /dev/null
+++ b/contrib/tzcode/strftime.c
@@ -0,0 +1,657 @@
+/* Convert a broken-down timestamp to a string.  */
+
+/* Copyright 1989 The Regents of the University of California.
+   All rights reserved.
+
+   Redistribution and use in source and binary forms, with or without
+   modification, are permitted provided that the following conditions
+   are met:
+   1. Redistributions of source code must retain the above copyright
+      notice, this list of conditions and the following disclaimer.
+   2. Redistributions in binary form must reproduce the above copyright
+      notice, this list of conditions and the following disclaimer in the
+      documentation and/or other materials provided with the distribution.
+   3. Neither the name of the University nor the names of its contributors
+      may be used to endorse or promote products derived from this software
+      without specific prior written permission.
+
+   THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS "AS IS" AND
+   ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+   IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+   ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+   FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+   DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+   OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+   HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+   LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+   OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+   SUCH DAMAGE.  */
+
+/*
+** Based on the UCB version with the copyright notice appearing above.
+**
+** This is ANSIish only when "multibyte character == plain character".
+*/
+
+#include "private.h"
+
+#include <fcntl.h>
+#include <locale.h>
+#include <stdio.h>
+
+#ifndef DEPRECATE_TWO_DIGIT_YEARS
+# define DEPRECATE_TWO_DIGIT_YEARS false
+#endif
+
+struct lc_time_T {
+	const char *	mon[MONSPERYEAR];
+	const char *	month[MONSPERYEAR];
+	const char *	wday[DAYSPERWEEK];
+	const char *	weekday[DAYSPERWEEK];
+	const char *	X_fmt;
+	const char *	x_fmt;
+	const char *	c_fmt;
+	const char *	am;
+	const char *	pm;
+	const char *	date_fmt;
+};
+
+static const struct lc_time_T	C_time_locale = {
+	{
+		"Jan", "Feb", "Mar", "Apr", "May", "Jun",
+		"Jul", "Aug", "Sep", "Oct", "Nov", "Dec"
+	}, {
+		"January", "February", "March", "April", "May", "June",
+		"July", "August", "September", "October", "November", "December"
+	}, {
+		"Sun", "Mon", "Tue", "Wed",
+		"Thu", "Fri", "Sat"
+	}, {
+		"Sunday", "Monday", "Tuesday", "Wednesday",
+		"Thursday", "Friday", "Saturday"
+	},
+
+	/* X_fmt */
+	"%H:%M:%S",
+
+	/*
+	** x_fmt
+	** C99 and later require this format.
+	** Using just numbers (as here) makes Quakers happier;
+	** it's also compatible with SVR4.
+	*/
+	"%m/%d/%y",
+
+	/*
+	** c_fmt
+	** C99 and later require this format.
+	** Previously this code used "%D %X", but we now conform to C99.
+	** Note that
+	**	"%a %b %d %H:%M:%S %Y"
+	** is used by Solaris 2.3.
+	*/
+	"%a %b %e %T %Y",
+
+	/* am */
+	"AM",
+
+	/* pm */
+	"PM",
+
+	/* date_fmt */
+	"%a %b %e %H:%M:%S %Z %Y"
+};
+
+enum warn { IN_NONE, IN_SOME, IN_THIS, IN_ALL };
+
+static char *	_add(const char *, char *, const char *);
+static char *	_conv(int, const char *, char *, const char *);
+static char *	_fmt(const char *, const struct tm *, char *, const char *,
+		     enum warn *);
+static char *	_yconv(int, int, bool, bool, char *, char const *);
+
+#ifndef YEAR_2000_NAME
+# define YEAR_2000_NAME "CHECK_STRFTIME_FORMATS_FOR_TWO_DIGIT_YEARS"
+#endif /* !defined YEAR_2000_NAME */
+
+#if HAVE_STRFTIME_L
+size_t
+strftime_l(char *s, size_t maxsize, char const *format, struct tm const *t,
+	   ATTRIBUTE_MAYBE_UNUSED locale_t locale)
+{
+  /* Just call strftime, as only the C locale is supported.  */
+  return strftime(s, maxsize, format, t);
+}
+#endif
+
+size_t
+strftime(char *s, size_t maxsize, const char *format, const struct tm *t)
+{
+	char *	p;
+	int saved_errno = errno;
+	enum warn warn = IN_NONE;
+
+	tzset();
+	p = _fmt(format, t, s, s + maxsize, &warn);
+	if (!p) {
+	  errno = EOVERFLOW;
+	  return 0;
+	}
+	if (DEPRECATE_TWO_DIGIT_YEARS
+	    && warn != IN_NONE && getenv(YEAR_2000_NAME)) {
+		fprintf(stderr, "\n");
+		fprintf(stderr, "strftime format \"%s\" ", format);
+		fprintf(stderr, "yields only two digits of years in ");
+		if (warn == IN_SOME)
+			fprintf(stderr, "some locales");
+		else if (warn == IN_THIS)
+			fprintf(stderr, "the current locale");
+		else	fprintf(stderr, "all locales");
+		fprintf(stderr, "\n");
+	}
+	if (p == s + maxsize) {
+		errno = ERANGE;
+		return 0;
+	}
+	*p = '\0';
+	errno = saved_errno;
+	return p - s;
+}
+
+static char *
+_fmt(const char *format, const struct tm *t, char *pt,
+     const char *ptlim, enum warn *warnp)
+{
+	struct lc_time_T const *Locale = &C_time_locale;
+
+	for ( ; *format; ++format) {
+		if (*format == '%') {
+label:
+			switch (*++format) {
+			case '\0':
+				--format;
+				break;
+			case 'A':
+				pt = _add((t->tm_wday < 0 ||
+					t->tm_wday >= DAYSPERWEEK) ?
+					"?" : Locale->weekday[t->tm_wday],
+					pt, ptlim);
+				continue;
+			case 'a':
+				pt = _add((t->tm_wday < 0 ||
+					t->tm_wday >= DAYSPERWEEK) ?
+					"?" : Locale->wday[t->tm_wday],
+					pt, ptlim);
+				continue;
+			case 'B':
+				pt = _add((t->tm_mon < 0 ||
+					t->tm_mon >= MONSPERYEAR) ?
+					"?" : Locale->month[t->tm_mon],
+					pt, ptlim);
+				continue;
+			case 'b':
+			case 'h':
+				pt = _add((t->tm_mon < 0 ||
+					t->tm_mon >= MONSPERYEAR) ?
+					"?" : Locale->mon[t->tm_mon],
+					pt, ptlim);
+				continue;
+			case 'C':
+				/*
+				** %C used to do a...
+				**	_fmt("%a %b %e %X %Y", t);
+				** ...whereas now POSIX 1003.2 calls for
+				** something completely different.
+				** (ado, 1993-05-24)
+				*/
+				pt = _yconv(t->tm_year, TM_YEAR_BASE,
+					    true, false, pt, ptlim);
+				continue;
+			case 'c':
+				{
+				enum warn warn2 = IN_SOME;
+
+				pt = _fmt(Locale->c_fmt, t, pt, ptlim, &warn2);
+				if (warn2 == IN_ALL)
+					warn2 = IN_THIS;
+				if (warn2 > *warnp)
+					*warnp = warn2;
+				}
+				continue;
+			case 'D':
+				pt = _fmt("%m/%d/%y", t, pt, ptlim, warnp);
+				continue;
+			case 'd':
+				pt = _conv(t->tm_mday, "%02d", pt, ptlim);
+				continue;
+			case 'E':
+			case 'O':
+				/*
+				** Locale modifiers of C99 and later.
+				** The sequences
+				**	%Ec %EC %Ex %EX %Ey %EY
+				**	%Od %oe %OH %OI %Om %OM
+				**	%OS %Ou %OU %OV %Ow %OW %Oy
+				** are supposed to provide alternative
+				** representations.
+				*/
+				goto label;
+			case 'e':
+				pt = _conv(t->tm_mday, "%2d", pt, ptlim);
+				continue;
+			case 'F':
+				pt = _fmt("%Y-%m-%d", t, pt, ptlim, warnp);
+				continue;
+			case 'H':
+				pt = _conv(t->tm_hour, "%02d", pt, ptlim);
+				continue;
+			case 'I':
+				pt = _conv((t->tm_hour % 12) ?
+					(t->tm_hour % 12) : 12,
+					"%02d", pt, ptlim);
+				continue;
+			case 'j':
+				pt = _conv(t->tm_yday + 1, "%03d", pt, ptlim);
+				continue;
+			case 'k':
+				/*
+				** This used to be...
+				**	_conv(t->tm_hour % 12 ?
+				**		t->tm_hour % 12 : 12, 2, ' ');
+				** ...and has been changed to the below to
+				** match SunOS 4.1.1 and Arnold Robbins'
+				** strftime version 3.0. That is, "%k" and
+				** "%l" have been swapped.
+				** (ado, 1993-05-24)
+				*/
+				pt = _conv(t->tm_hour, "%2d", pt, ptlim);
+				continue;
+#ifdef KITCHEN_SINK
+			case 'K':
+				/*
+				** After all this time, still unclaimed!
+				*/
+				pt = _add("kitchen sink", pt, ptlim);
+				continue;
+#endif /* defined KITCHEN_SINK */
+			case 'l':
+				/*
+				** This used to be...
+				**	_conv(t->tm_hour, 2, ' ');
+				** ...and has been changed to the below to
+				** match SunOS 4.1.1 and Arnold Robbin's
+				** strftime version 3.0. That is, "%k" and
+				** "%l" have been swapped.
+				** (ado, 1993-05-24)
+				*/
+				pt = _conv((t->tm_hour % 12) ?
+					(t->tm_hour % 12) : 12,
+					"%2d", pt, ptlim);
+				continue;
+			case 'M':
+				pt = _conv(t->tm_min, "%02d", pt, ptlim);
+				continue;
+			case 'm':
+				pt = _conv(t->tm_mon + 1, "%02d", pt, ptlim);
+				continue;
+			case 'n':
+				pt = _add("\n", pt, ptlim);
+				continue;
+			case 'p':
+				pt = _add((t->tm_hour >= (HOURSPERDAY / 2)) ?
+					Locale->pm :
+					Locale->am,
+					pt, ptlim);
+				continue;
+			case 'R':
+				pt = _fmt("%H:%M", t, pt, ptlim, warnp);
+				continue;
+			case 'r':
+				pt = _fmt("%I:%M:%S %p", t, pt, ptlim, warnp);
+				continue;
+			case 'S':
+				pt = _conv(t->tm_sec, "%02d", pt, ptlim);
+				continue;
+			case 's':
+				{
+					struct tm	tm;
+					char		buf[INT_STRLEN_MAXIMUM(
+								time_t) + 1];
+					time_t		mkt;
+
+					tm.tm_sec = t->tm_sec;
+					tm.tm_min = t->tm_min;
+					tm.tm_hour = t->tm_hour;
+					tm.tm_mday = t->tm_mday;
+					tm.tm_mon = t->tm_mon;
+					tm.tm_year = t->tm_year;
+					tm.tm_isdst = t->tm_isdst;
+#if defined TM_GMTOFF && ! UNINIT_TRAP
+					tm.TM_GMTOFF = t->TM_GMTOFF;
+#endif
+					mkt = mktime(&tm);
+					/* If mktime fails, %s expands to the
+					   value of (time_t) -1 as a failure
+					   marker; this is better in practice
+					   than strftime failing.  */
+					if (TYPE_SIGNED(time_t)) {
+					  intmax_t n = mkt;
+					  sprintf(buf, "%"PRIdMAX, n);
+					} else {
+					  uintmax_t n = mkt;
+					  sprintf(buf, "%"PRIuMAX, n);
+					}
+					pt = _add(buf, pt, ptlim);
+				}
+				continue;
+			case 'T':
+				pt = _fmt("%H:%M:%S", t, pt, ptlim, warnp);
+				continue;
+			case 't':
+				pt = _add("\t", pt, ptlim);
+				continue;
+			case 'U':
+				pt = _conv((t->tm_yday + DAYSPERWEEK -
+					t->tm_wday) / DAYSPERWEEK,
+					"%02d", pt, ptlim);
+				continue;
+			case 'u':
+				/*
+				** From Arnold Robbins' strftime version 3.0:
+				** "ISO 8601: Weekday as a decimal number
+				** [1 (Monday) - 7]"
+				** (ado, 1993-05-24)
+				*/
+				pt = _conv((t->tm_wday == 0) ?
+					DAYSPERWEEK : t->tm_wday,
+					"%d", pt, ptlim);
+				continue;
+			case 'V':	/* ISO 8601 week number */
+			case 'G':	/* ISO 8601 year (four digits) */
+			case 'g':	/* ISO 8601 year (two digits) */
+/*
+** From Arnold Robbins' strftime version 3.0: "the week number of the
+** year (the first Monday as the first day of week 1) as a decimal number
+** (01-53)."
+** (ado, 1993-05-24)
+**
+** From <https://www.cl.cam.ac.uk/~mgk25/iso-time.html> by Markus Kuhn:
+** "Week 01 of a year is per definition the first week which has the
+** Thursday in this year, which is equivalent to the week which contains
+** the fourth day of January. In other words, the first week of a new year
+** is the week which has the majority of its days in the new year. Week 01
+** might also contain days from the previous year and the week before week
+** 01 of a year is the last week (52 or 53) of the previous year even if
+** it contains days from the new year. A week starts with Monday (day 1)
+** and ends with Sunday (day 7). For example, the first week of the year
+** 1997 lasts from 1996-12-30 to 1997-01-05..."
+** (ado, 1996-01-02)
+*/
+				{
+					int	year;
+					int	base;
+					int	yday;
+					int	wday;
+					int	w;
+
+					year = t->tm_year;
+					base = TM_YEAR_BASE;
+					yday = t->tm_yday;
+					wday = t->tm_wday;
+					for ( ; ; ) {
+						int	len;
+						int	bot;
+						int	top;
+
+						len = isleap_sum(year, base) ?
+							DAYSPERLYEAR :
+							DAYSPERNYEAR;
+						/*
+						** What yday (-3 ... 3) does
+						** the ISO year begin on?
+						*/
+						bot = ((yday + 11 - wday) %
+							DAYSPERWEEK) - 3;
+						/*
+						** What yday does the NEXT
+						** ISO year begin on?
+						*/
+						top = bot -
+							(len % DAYSPERWEEK);
+						if (top < -3)
+							top += DAYSPERWEEK;
+						top += len;
+						if (yday >= top) {
+							++base;
+							w = 1;
+							break;
+						}
+						if (yday >= bot) {
+							w = 1 + ((yday - bot) /
+								DAYSPERWEEK);
+							break;
+						}
+						--base;
+						yday += isleap_sum(year, base) ?
+							DAYSPERLYEAR :
+							DAYSPERNYEAR;
+					}
+#ifdef XPG4_1994_04_09
+					if ((w == 52 &&
+						t->tm_mon == TM_JANUARY) ||
+						(w == 1 &&
+						t->tm_mon == TM_DECEMBER))
+							w = 53;
+#endif /* defined XPG4_1994_04_09 */
+					if (*format == 'V')
+						pt = _conv(w, "%02d",
+							pt, ptlim);
+					else if (*format == 'g') {
+						*warnp = IN_ALL;
+						pt = _yconv(year, base,
+							false, true,
+							pt, ptlim);
+					} else	pt = _yconv(year, base,
+							true, true,
+							pt, ptlim);
+				}
+				continue;
+			case 'v':
+				/*
+				** From Arnold Robbins' strftime version 3.0:
+				** "date as dd-bbb-YYYY"
+				** (ado, 1993-05-24)
+				*/
+				pt = _fmt("%e-%b-%Y", t, pt, ptlim, warnp);
+				continue;
+			case 'W':
+				pt = _conv((t->tm_yday + DAYSPERWEEK -
+					(t->tm_wday ?
+					(t->tm_wday - 1) :
+					(DAYSPERWEEK - 1))) / DAYSPERWEEK,
+					"%02d", pt, ptlim);
+				continue;
+			case 'w':
+				pt = _conv(t->tm_wday, "%d", pt, ptlim);
+				continue;
+			case 'X':
+				pt = _fmt(Locale->X_fmt, t, pt, ptlim, warnp);
+				continue;
+			case 'x':
+				{
+				enum warn warn2 = IN_SOME;
+
+				pt = _fmt(Locale->x_fmt, t, pt, ptlim, &warn2);
+				if (warn2 == IN_ALL)
+					warn2 = IN_THIS;
+				if (warn2 > *warnp)
+					*warnp = warn2;
+				}
+				continue;
+			case 'y':
+				*warnp = IN_ALL;
+				pt = _yconv(t->tm_year, TM_YEAR_BASE,
+					false, true,
+					pt, ptlim);
+				continue;
+			case 'Y':
+				pt = _yconv(t->tm_year, TM_YEAR_BASE,
+					true, true,
+					pt, ptlim);
+				continue;
+			case 'Z':
+#ifdef TM_ZONE
+				pt = _add(t->TM_ZONE, pt, ptlim);
+#elif HAVE_TZNAME
+				if (t->tm_isdst >= 0)
+					pt = _add(tzname[t->tm_isdst != 0],
+						pt, ptlim);
+#endif
+				/*
+				** C99 and later say that %Z must be
+				** replaced by the empty string if the
+				** time zone abbreviation is not
+				** determinable.
+				*/
+				continue;
+			case 'z':
+#if defined TM_GMTOFF || USG_COMPAT || ALTZONE
+				{
+				long		diff;
+				char const *	sign;
+				bool negative;
+
+# ifdef TM_GMTOFF
+				diff = t->TM_GMTOFF;
+# else
+				/*
+				** C99 and later say that the UT offset must
+				** be computed by looking only at
+				** tm_isdst. This requirement is
+				** incorrect, since it means the code
+				** must rely on magic (in this case
+				** altzone and timezone), and the
+				** magic might not have the correct
+				** offset. Doing things correctly is
+				** tricky and requires disobeying the standard;
+				** see GNU C strftime for details.
+				** For now, punt and conform to the
+				** standard, even though it's incorrect.
+				**
+				** C99 and later say that %z must be replaced by
+				** the empty string if the time zone is not
+				** determinable, so output nothing if the
+				** appropriate variables are not available.
+				*/
+				if (t->tm_isdst < 0)
+					continue;
+				if (t->tm_isdst == 0)
+#  if USG_COMPAT
+					diff = -timezone;
+#  else
+					continue;
+#  endif
+				else
+#  if ALTZONE
+					diff = -altzone;
+#  else
+					continue;
+#  endif
+# endif
+				negative = diff < 0;
+				if (diff == 0) {
+# ifdef TM_ZONE
+				  negative = t->TM_ZONE[0] == '-';
+# else
+				  negative = t->tm_isdst < 0;
+#  if HAVE_TZNAME
+				  if (tzname[t->tm_isdst != 0][0] == '-')
+				    negative = true;
+#  endif
+# endif
+				}
+				if (negative) {
+					sign = "-";
+					diff = -diff;
+				} else	sign = "+";
+				pt = _add(sign, pt, ptlim);
+				diff /= SECSPERMIN;
+				diff = (diff / MINSPERHOUR) * 100 +
+					(diff % MINSPERHOUR);
+				pt = _conv(diff, "%04d", pt, ptlim);
+				}
+#endif
+				continue;
+			case '+':
+				pt = _fmt(Locale->date_fmt, t, pt, ptlim,
+					warnp);
+				continue;
+			case '%':
+			/*
+			** X311J/88-090 (4.12.3.5): if conversion char is
+			** undefined, behavior is undefined. Print out the
+			** character itself as printf(3) also does.
+			*/
+			default:
+				break;
+			}
+		}
+		if (pt == ptlim)
+			break;
+		*pt++ = *format;
+	}
+	return pt;
+}
+
+static char *
+_conv(int n, const char *format, char *pt, const char *ptlim)
+{
+	char	buf[INT_STRLEN_MAXIMUM(int) + 1];
+
+	sprintf(buf, format, n);
+	return _add(buf, pt, ptlim);
+}
+
+static char *
+_add(const char *str, char *pt, const char *ptlim)
+{
+	while (pt < ptlim && (*pt = *str++) != '\0')
+		++pt;
+	return pt;
+}
+
+/*
+** POSIX and the C Standard are unclear or inconsistent about
+** what %C and %y do if the year is negative or exceeds 9999.
+** Use the convention that %C concatenated with %y yields the
+** same output as %Y, and that %Y contains at least 4 bytes,
+** with more only if necessary.
+*/
+
+static char *
+_yconv(int a, int b, bool convert_top, bool convert_yy,
+       char *pt, const char *ptlim)
+{
+	register int	lead;
+	register int	trail;
+
+	int DIVISOR = 100;
+	trail = a % DIVISOR + b % DIVISOR;
+	lead = a / DIVISOR + b / DIVISOR + trail / DIVISOR;
+	trail %= DIVISOR;
+	if (trail < 0 && lead > 0) {
+		trail += DIVISOR;
+		--lead;
+	} else if (lead < 0 && trail > 0) {
+		trail -= DIVISOR;
+		++lead;
+	}
+	if (convert_top) {
+		if (lead == 0 && trail < 0)
+			pt = _add("-0", pt, ptlim);
+		else	pt = _conv(lead, "%02d", pt, ptlim);
+	}
+	if (convert_yy)
+		pt = _conv(((trail < 0) ? -trail : trail), "%02d", pt, ptlim);
+	return pt;
+}
diff --git a/contrib/tzcode/theory.html b/contrib/tzcode/theory.html
new file mode 100644
index 000000000000..75e347f0f9d1
--- /dev/null
+++ b/contrib/tzcode/theory.html
@@ -0,0 +1,1479 @@
+<!DOCTYPE html>
+<html lang="en">
+<head>
+  <title>Theory and pragmatics of the tz code and data</title>
+  <meta charset="UTF-8">
+  <style>
+    pre {margin-left: 2em; white-space: pre-wrap;}
+  </style>
+</head>
+
+<body>
+<h1>Theory and pragmatics of the <code><abbr>tz</abbr></code> code and data</h1>
+  <h3>Outline</h3>
+  <nav>
+    <ul>
+      <li><a href="#scope">Scope of the <code><abbr>tz</abbr></code>
+	  database</a></li>
+      <li><a href="#naming">Timezone identifiers</a></li>
+      <li><a href="#abbreviations">Time zone abbreviations</a></li>
+      <li><a href="#accuracy">Accuracy of the <code><abbr>tz</abbr></code>
+	  database</a></li>
+      <li><a href="#functions">Time and date functions</a></li>
+      <li><a href="#stability">Interface stability</a></li>
+      <li><a href="#leapsec">Leap seconds</a></li>
+      <li><a href="#calendar">Calendrical issues</a></li>
+      <li><a href="#planets">Time and time zones on other planets</a></li>
+    </ul>
+  </nav>
+
+<section>
+  <h2 id="scope">Scope of the <code><abbr>tz</abbr></code> database</h2>
+<p>
+The <a
+href="https://www.iana.org/time-zones"><code><abbr>tz</abbr></code>
+database</a> attempts to record the history and predicted future of
+civil time scales.
+It organizes <a href="tz-link.html">time zone and daylight saving time
+data</a> by partitioning the world into <a
+href="https://en.wikipedia.org/wiki/List_of_tz_database_time_zones"><dfn>timezones</dfn></a>
+whose clocks all agree about timestamps that occur after the <a
+href="https://en.wikipedia.org/wiki/Unix_time">POSIX Epoch</a>
+(1970-01-01 00:00:00 <a
+href="https://en.wikipedia.org/wiki/Coordinated_Universal_Time"><abbr
+title="Coordinated Universal Time">UTC</abbr></a>).
+Although 1970 is a somewhat-arbitrary cutoff, there are significant
+challenges to moving the cutoff earlier even by a decade or two, due
+to the wide variety of local practices before computer timekeeping
+became prevalent.
+Most timezones correspond to a notable location and the database
+records all known clock transitions for that location;
+some timezones correspond instead to a fixed <abbr>UTC</abbr> offset.
+</p>
+
+<p>
+Each timezone typically corresponds to a geographical region that is
+smaller than a traditional time zone, because clocks in a timezone
+all agree after 1970 whereas a traditional time zone merely
+specifies current standard time. For example, applications that deal
+with current and future timestamps in the traditional North
+American mountain time zone can choose from the timezones
+<code>America/Denver</code> which observes US-style daylight saving
+time (<abbr>DST</abbr>),
+and <code>America/Phoenix</code> which does not observe <abbr>DST</abbr>.
+Applications that also deal with past timestamps in the mountain time
+zone can choose from over a dozen timezones, such as
+<code>America/Boise</code>, <code>America/Edmonton</code>, and
+<code>America/Hermosillo</code>, each of which currently uses mountain
+time but differs from other timezones for some timestamps after 1970.
+</p>
+
+<p>
+Clock transitions before 1970 are recorded for location-based timezones,
+because most systems support timestamps before 1970 and could
+misbehave if data entries were omitted for pre-1970 transitions.
+However, the database is not designed for and does not suffice for
+applications requiring accurate handling of all past times everywhere,
+as it would take far too much effort and guesswork to record all
+details of pre-1970 civil timekeeping.
+Although some information outside the scope of the database is
+collected in a file <code>backzone</code> that is distributed along
+with the database proper, this file is less reliable and does not
+necessarily follow database guidelines.
+</p>
+
+<p>
+As described below, reference source code for using the
+<code><abbr>tz</abbr></code> database is also available.
+The <code><abbr>tz</abbr></code> code is upwards compatible with <a
+href="https://en.wikipedia.org/wiki/POSIX">POSIX</a>, an international
+standard for <a
+href="https://en.wikipedia.org/wiki/Unix">UNIX</a>-like systems.
+As of this writing, the current edition of POSIX is: <a
+href="https://pubs.opengroup.org/onlinepubs/9699919799/"> The Open
+Group Base Specifications Issue 7</a>, IEEE Std 1003.1-2017, 2018
+Edition.
+Because the database's scope encompasses real-world changes to civil
+timekeeping, its model for describing time is more complex than the
+standard and daylight saving times supported by POSIX.
+A <code><abbr>tz</abbr></code> timezone corresponds to a ruleset that can
+have more than two changes per year, these changes need not merely
+flip back and forth between two alternatives, and the rules themselves
+can change at times.
+Whether and when a timezone changes its clock,
+and even the timezone's notional base offset from <abbr>UTC</abbr>,
+are variable.
+It does not always make sense to talk about a timezone's
+"base offset", which is not necessarily a single number.
+</p>
+
+</section>
+
+<section>
+  <h2 id="naming">Timezone identifiers</h2>
+<p>
+Each timezone has a name that uniquely identifies the timezone.
+Inexperienced users are not expected to select these names unaided.
+Distributors should provide documentation and/or a simple selection
+interface that explains each name via a map or via descriptive text like
+"Czech Republic" instead of the timezone name "<code>Europe/Prague</code>".
+If geolocation information is available, a selection interface can
+locate the user on a timezone map or prioritize names that are
+geographically close. For an example selection interface, see the
+<code>tzselect</code> program in the <code><abbr>tz</abbr></code> code.
+The <a href="https://cldr.unicode.org">Unicode Common Locale Data
+Repository</a> contains data that may be useful for other selection
+interfaces; it maps timezone names like <code>Europe/Prague</code> to
+locale-dependent strings like "Prague", "Praha", "Прага", and "布拉格".
+</p>
+
+<p>
+The naming conventions attempt to strike a balance
+among the following goals:
+</p>
+
+<ul>
+  <li>
+    Uniquely identify every timezone where clocks have agreed since 1970.
+    This is essential for the intended use: static clocks keeping local
+    civil time.
+  </li>
+  <li>
+    Indicate to experts where the timezone's clocks typically are.
+  </li>
+  <li>
+    Be robust in the presence of political changes.
+    For example, names are typically not tied to countries, to avoid
+    incompatibilities when countries change their name (e.g.,
+    Swaziland&rarr;Eswatini) or when locations change countries (e.g., Hong
+    Kong from UK colony to China).
+    There is no requirement that every country or national
+    capital must have a timezone name.
+  </li>
+  <li>
+    Be portable to a wide variety of implementations.
+  </li>
+  <li>
+    Use a consistent naming conventions over the entire world.
+  </li>
+</ul>
+
+<p>
+Names normally have the form
+<var>AREA</var><code>/</code><var>LOCATION</var>, where
+<var>AREA</var> is a continent or ocean, and
+<var>LOCATION</var> is a specific location within the area.
+North and South America share the same area, '<code>America</code>'.
+Typical names are '<code>Africa/Cairo</code>',
+'<code>America/New_York</code>', and '<code>Pacific/Honolulu</code>'.
+Some names are further qualified to help avoid confusion; for example,
+'<code>America/Indiana/Petersburg</code>' distinguishes Petersburg,
+Indiana from other Petersburgs in America.
+</p>
+
+<p>
+Here are the general guidelines used for
+choosing timezone names,
+in decreasing order of importance:
+</p>
+
+<ul>
+  <li>
+    Use only valid POSIX file name components (i.e., the parts of
+    names other than '<code>/</code>').
+    Do not use the file name components '<code>.</code>' and
+    '<code>..</code>'.
+    Within a file name component, use only <a
+    href="https://en.wikipedia.org/wiki/ASCII">ASCII</a> letters,
+    '<code>.</code>', '<code>-</code>' and '<code>_</code>'.
+    Do not use digits, as that might create an ambiguity with <a
+    href="https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap08.html#tag_08_03">POSIX
+    <code>TZ</code> strings</a>.
+    A file name component must not exceed 14 characters or start with
+    '<code>-</code>'.
+    E.g., prefer <code>America/Noronha</code> to
+    <code>America/Fernando_de_Noronha</code>.
+    Exceptions: see the discussion of legacy names below.
+  </li>
+  <li>
+    A name must not be empty, or contain '<code>//</code>', or
+    start or end with '<code>/</code>'.
+  </li>
+  <li>
+    Do not use names that differ only in case.
+    Although the reference implementation is case-sensitive, some
+    other implementations are not, and they would mishandle names
+    differing only in case.
+  </li>
+  <li>
+    If one name <var>A</var> is an initial prefix of another
+    name <var>AB</var> (ignoring case), then <var>B</var> must not
+    start with '<code>/</code>', as a regular file cannot have the
+    same name as a directory in POSIX.
+    For example, <code>America/New_York</code> precludes
+    <code>America/New_York/Bronx</code>.
+  </li>
+  <li>
+    Uninhabited regions like the North Pole and Bouvet Island
+    do not need locations, since local time is not defined there.
+  </li>
+  <li>
+    If all the clocks in a timezone have agreed since 1970,
+    do not bother to include more than one timezone
+    even if some of the clocks disagreed before 1970.
+    Otherwise these tables would become annoyingly large.
+  </li>
+  <li>
+    If boundaries between regions are fluid, such as during a war or
+    insurrection, do not bother to create a new timezone merely
+    because of yet another boundary change. This helps prevent table
+    bloat and simplifies maintenance.
+  </li>
+  <li>
+    If a name is ambiguous, use a less ambiguous alternative;
+    e.g., many cities are named San José and Georgetown, so
+    prefer <code>America/Costa_Rica</code> to
+    <code>America/San_Jose</code> and <code>America/Guyana</code>
+    to <code>America/Georgetown</code>.
+  </li>
+  <li>
+    Keep locations compact.
+    Use cities or small islands, not countries or regions, so that any
+    future changes do not split individual locations into different
+    timezones.
+    E.g., prefer <code>Europe/Paris</code> to <code>Europe/France</code>,
+    since
+    <a href="https://en.wikipedia.org/wiki/Time_in_France#History">France
+    has had multiple time zones</a>.
+  </li>
+  <li>
+    Use mainstream English spelling, e.g., prefer
+    <code>Europe/Rome</code> to <code>Europa/Roma</code>, and
+    prefer <code>Europe/Athens</code> to the Greek
+    <code>Ευρώπη/Αθήνα</code> or the Romanized
+    <code>Evrópi/Athína</code>.
+    The POSIX file name restrictions encourage this guideline.
+  </li>
+  <li>
+    Use the most populous among locations in a region,
+    e.g., prefer <code>Asia/Shanghai</code> to
+    <code>Asia/Beijing</code>.
+    Among locations with similar populations, pick the best-known
+    location, e.g., prefer <code>Europe/Rome</code> to
+    <code>Europe/Milan</code>.
+  </li>
+  <li>
+    Use the singular form, e.g., prefer <code>Atlantic/Canary</code> to
+    <code>Atlantic/Canaries</code>.
+  </li>
+  <li>
+    Omit common suffixes like '<code>_Islands</code>' and
+    '<code>_City</code>', unless that would lead to ambiguity.
+    E.g., prefer <code>America/Cayman</code> to
+    <code>America/Cayman_Islands</code> and
+    <code>America/Guatemala</code> to
+    <code>America/Guatemala_City</code>, but prefer
+    <code>America/Mexico_City</code> to
+    <code>America/Mexico</code>
+    because <a href="https://en.wikipedia.org/wiki/Time_in_Mexico">the
+    country of Mexico has several time zones</a>.
+  </li>
+  <li>
+    Use '<code>_</code>' to represent a space.
+  </li>
+  <li>
+    Omit '<code>.</code>' from abbreviations in names.
+    E.g., prefer <code>Atlantic/St_Helena</code> to
+    <code>Atlantic/St._Helena</code>.
+  </li>
+  <li>
+    Do not change established names if they only marginally violate
+    the above guidelines.
+    For example, do not change the existing name <code>Europe/Rome</code> to
+    <code>Europe/Milan</code> merely because Milan's population has grown
+    to be somewhat greater than Rome's.
+  </li>
+  <li>
+    If a name is changed, put its old spelling in the
+    '<code>backward</code>' file as a link to the new spelling.
+    This means old spellings will continue to work.
+    Ordinarily a name change should occur only in the rare case when
+    a location's consensus English-language spelling changes; for example,
+    in 2008 <code>Asia/Calcutta</code> was renamed to <code>Asia/Kolkata</code>
+    due to long-time widespread use of the new city name instead of the old.
+  </li>
+</ul>
+
+<p>
+Guidelines have evolved with time, and names following old versions of
+these guidelines might not follow the current version. When guidelines
+have changed, old names continue to be supported. Guideline changes
+have included the following:
+</p>
+
+<ul>
+<li>
+Older versions of this package used a different naming scheme.
+See the file '<code>backward</code>' for most of these older names
+(e.g., '<code>US/Eastern</code>' instead of '<code>America/New_York</code>').
+The other old-fashioned names still supported are
+'<code>WET</code>', '<code>CET</code>', '<code>MET</code>', and
+'<code>EET</code>' (see the file '<code>europe</code>').
+</li>
+
+<li>
+Older versions of this package defined legacy names that are
+incompatible with the first guideline of location names, but which are
+still supported.
+These legacy names are mostly defined in the file
+'<code>etcetera</code>'.
+Also, the file '<code>backward</code>' defines the legacy names
+'<code>Etc/GMT0</code>', '<code>Etc/GMT-0</code>', '<code>Etc/GMT+0</code>',
+'<code>GMT0</code>', '<code>GMT-0</code>' and '<code>GMT+0</code>',
+and the file '<code>northamerica</code>' defines the legacy names
+'<code>EST5EDT</code>', '<code>CST6CDT</code>',
+'<code>MST7MDT</code>', and '<code>PST8PDT</code>'.
+</li>
+
+<li>
+Older versions of these guidelines said that
+there should typically be at least one name for each <a
+href="https://en.wikipedia.org/wiki/ISO_3166-1"><abbr
+title="International Organization for Standardization">ISO</abbr>
+3166-1</a> officially assigned two-letter code for an inhabited
+country or territory.
+This old guideline has been dropped, as it was not needed to handle
+timestamps correctly and it increased maintenance burden.
+</li>
+</ul>
+
+<p>
+The file <code>zone1970.tab</code> lists geographical locations used
+to name timezones.
+It is intended to be an exhaustive list of names for geographic
+regions as described above; this is a subset of the timezones in the data.
+Although a <code>zone1970.tab</code> location's
+<a href="https://en.wikipedia.org/wiki/Longitude">longitude</a>
+corresponds to
+its <a href="https://en.wikipedia.org/wiki/Local_mean_time">local mean
+time (<abbr>LMT</abbr>)</a> offset with one hour for every 15&deg;
+east longitude, this relationship is not exact.
+The backward-compatibility file <code>zone.tab</code> is similar
+but conforms to the older-version guidelines related to <abbr>ISO</abbr> 3166-1;
+it lists only one country code per entry and unlike <code>zone1970.tab</code>
+it can list names defined in <code>backward</code>.
+</p>
+
+<p>
+The database defines each timezone name to be a zone, or a link to a zone.
+The source file <code>backward</code> defines links for backward
+compatibility; it does not define zones.
+Although <code>backward</code> was originally designed to be optional,
+nowadays distributions typically use it
+and no great weight should be attached to whether a link
+is defined in <code>backward</code> or in some other file.
+The source file <code>etcetera</code> defines names that may be useful
+on platforms that do not support POSIX-style <code>TZ</code> strings;
+no other source file other than <code>backward</code>
+contains links to its zones.
+One of <code>etcetera</code>'s names is <code>Etc/UTC</code>,
+used by functions like <code>gmtime</code> to obtain leap
+second information on platforms that support leap seconds.
+Another <code>etcetera</code> name, <code>GMT</code>,
+is used by older code releases.
+</p>
+</section>
+
+<section>
+  <h2 id="abbreviations">Time zone abbreviations</h2>
+<p>
+When this package is installed, it generates time zone abbreviations
+like '<code>EST</code>' to be compatible with human tradition and POSIX.
+Here are the general guidelines used for choosing time zone abbreviations,
+in decreasing order of importance:
+</p>
+
+<ul>
+  <li>
+    Use three to six characters that are ASCII alphanumerics or
+    '<code>+</code>' or '<code>-</code>'.
+    Previous editions of this database also used characters like
+    space and '<code>?</code>', but these characters have a
+    special meaning to the
+    <a href="https://en.wikipedia.org/wiki/Unix_shell">UNIX shell</a>
+    and cause commands like
+    '<code><a href="https://pubs.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html#set">set</a>
+    `<a href="https://pubs.opengroup.org/onlinepubs/9699919799/utilities/date.html">date</a>`</code>'
+    to have unexpected effects.
+    Previous editions of this guideline required upper-case letters, but the
+    Congressman who introduced
+    <a href="https://en.wikipedia.org/wiki/Chamorro_Time_Zone">Chamorro
+    Standard Time</a> preferred "ChST", so lower-case letters are now
+    allowed.
+    Also, POSIX from 2001 on relaxed the rule to allow '<code>-</code>',
+    '<code>+</code>', and alphanumeric characters from the portable
+    character set in the current locale.
+    In practice ASCII alphanumerics and '<code>+</code>' and
+    '<code>-</code>' are safe in all locales.
+
+    <p>
+    In other words, in the C locale the POSIX extended regular
+    expression <code>[-+[:alnum:]]{3,6}</code> should match the
+    abbreviation.
+    This guarantees that all abbreviations could have been specified by a
+    POSIX <code>TZ</code> string.
+    </p>
+  </li>
+  <li>
+    Use abbreviations that are in common use among English-speakers,
+    e.g., 'EST' for Eastern Standard Time in North America.
+    We assume that applications translate them to other languages
+    as part of the normal localization process; for example,
+    a French application might translate 'EST' to 'HNE'.
+
+    <p>
+    <small>These abbreviations (for standard/daylight/etc. time) are:
+      ACST/ACDT Australian Central,
+      AST/ADT/APT/AWT/ADDT Atlantic,
+      AEST/AEDT Australian Eastern,
+      AHST/AHDT Alaska-Hawaii,
+      AKST/AKDT Alaska,
+      AWST/AWDT Australian Western,
+      BST/BDT Bering,
+      CAT/CAST Central Africa,
+      CET/CEST/CEMT Central European,
+      ChST Chamorro,
+      CST/CDT/CWT/CPT/CDDT Central [North America],
+      CST/CDT China,
+      GMT/BST/IST/BDST Greenwich,
+      EAT East Africa,
+      EST/EDT/EWT/EPT/EDDT Eastern [North America],
+      EET/EEST Eastern European,
+      GST/GDT Guam,
+      HST/HDT/HWT/HPT Hawaii,
+      HKT/HKST/HKWT Hong Kong,
+      IST India,
+      IST/GMT Irish,
+      IST/IDT/IDDT Israel,
+      JST/JDT Japan,
+      KST/KDT Korea,
+      MET/MEST Middle European (a backward-compatibility alias for
+	Central European),
+      MSK/MSD Moscow,
+      MST/MDT/MWT/MPT/MDDT Mountain,
+      NST/NDT/NWT/NPT/NDDT Newfoundland,
+      NST/NDT/NWT/NPT Nome,
+      NZMT/NZST New Zealand through 1945,
+      NZST/NZDT New Zealand 1946&ndash;present,
+      PKT/PKST Pakistan,
+      PST/PDT/PWT/PPT/PDDT Pacific,
+      PST/PDT Philippine,
+      SAST South Africa,
+      SST Samoa,
+      UTC Universal,
+      WAT/WAST West Africa,
+      WET/WEST/WEMT Western European,
+      WIB Waktu Indonesia Barat,
+      WIT Waktu Indonesia Timur,
+      WITA Waktu Indonesia Tengah,
+      YST/YDT/YWT/YPT/YDDT Yukon</small>.
+    </p>
+  </li>
+  <li>
+    <p>
+    For times taken from a city's longitude, use the
+    traditional <var>x</var>MT notation.
+    The only abbreviation like this in current use is '<abbr>GMT</abbr>'.
+    The others are for timestamps before 1960,
+    except that Monrovia Mean Time persisted until 1972.
+    Typically, numeric abbreviations (e.g., '<code>-</code>004430' for
+    MMT) would cause trouble here, as the numeric strings would exceed
+    the POSIX length limit.
+    </p>
+
+    <p>
+    <small>These abbreviations are:
+      AMT Asunción, Athens;
+      BMT Baghdad, Bangkok, Batavia, Bermuda, Bern, Bogotá, Bridgetown,
+        Brussels, Bucharest;
+      CMT Calamarca, Caracas, Chisinau, Colón, Córdoba;
+      DMT Dublin/Dunsink;
+      EMT Easter;
+      FFMT Fort-de-France;
+      FMT Funchal;
+      GMT Greenwich;
+      HMT Havana, Helsinki, Horta, Howrah;
+      IMT Irkutsk, Istanbul;
+      JMT Jerusalem;
+      KMT Kaunas, Kyiv, Kingston;
+      LMT Lima, Lisbon, local, Luanda;
+      MMT Macassar, Madras, Malé, Managua, Minsk, Monrovia, Montevideo,
+	Moratuwa, Moscow;
+      PLMT Phù Liễn;
+      PMT Paramaribo, Paris, Perm, Pontianak, Prague;
+      PMMT Port Moresby;
+      QMT Quito;
+      RMT Rangoon, Riga, Rome;
+      SDMT Santo Domingo;
+      SJMT San José;
+      SMT Santiago, Simferopol, Singapore, Stanley;
+      TBMT Tbilisi;
+      TMT Tallinn, Tehran;
+      WMT Warsaw;
+      ZMT Zomba.</small>
+    </p>
+
+    <p>
+    <small>A few abbreviations also follow the pattern that
+    <abbr>GMT</abbr>/<abbr>BST</abbr> established for time in the UK.
+    They are:
+      BMT/BST for Bermuda 1890&ndash;1930,
+      CMT/BST for Calamarca Mean Time and Bolivian Summer Time
+	1890&ndash;1932,
+      DMT/IST for Dublin/Dunsink Mean Time and Irish Summer Time
+	1880&ndash;1916,
+      MMT/MST/MDST for Moscow 1880&ndash;1919, and
+      RMT/LST for Riga Mean Time and Latvian Summer time 1880&ndash;1926.
+    </small>
+    </p>
+  </li>
+  <li>
+    Use '<abbr>LMT</abbr>' for local mean time of locations before the
+    introduction of standard time; see "<a href="#scope">Scope of the
+    <code><abbr>tz</abbr></code> database</a>".
+  </li>
+  <li>
+    If there is no common English abbreviation, use numeric offsets like
+    <code>-</code>05 and <code>+</code>0530 that are generated
+    by <code>zic</code>'s <code>%z</code> notation.
+  </li>
+  <li>
+    Use current abbreviations for older timestamps to avoid confusion.
+    For example, in 1910 a common English abbreviation for time
+    in central Europe was 'MEZ' (short for both "Middle European
+    Zone" and for "Mitteleuropäische Zeit" in German).
+    Nowadays 'CET' ("Central European Time") is more common in
+    English, and the database uses 'CET' even for circa-1910
+    timestamps as this is less confusing for modern users and avoids
+    the need for determining when 'CET' supplanted 'MEZ' in common
+    usage.
+  </li>
+  <li>
+    Use a consistent style in a timezone's history.
+    For example, if a history tends to use numeric
+    abbreviations and a particular entry could go either way, use a
+    numeric abbreviation.
+  </li>
+  <li>
+    Use
+    <a href="https://en.wikipedia.org/wiki/Universal_Time">Universal Time</a>
+    (<abbr>UT</abbr>) (with time zone abbreviation '<code>-</code>00') for
+    locations while uninhabited.
+    The leading '<code>-</code>' is a flag that the <abbr>UT</abbr> offset is in
+    some sense undefined; this notation is derived
+    from <a href="https://datatracker.ietf.org/doc/html/rfc3339">Internet
+    <abbr title="Request For Comments">RFC</abbr> 3339</a>.
+  </li>
+</ul>
+
+<p>
+Application writers should note that these abbreviations are ambiguous
+in practice: e.g., 'CST' means one thing in China and something else
+in North America, and 'IST' can refer to time in India, Ireland or
+Israel.
+To avoid ambiguity, use numeric <abbr>UT</abbr> offsets like
+'<code>-</code>0600' instead of time zone abbreviations like 'CST'.
+</p>
+</section>
+
+<section>
+  <h2 id="accuracy">Accuracy of the <code><abbr>tz</abbr></code> database</h2>
+<p>
+The <code><abbr>tz</abbr></code> database is not authoritative, and it
+surely has errors.
+Corrections are welcome and encouraged; see the file <code>CONTRIBUTING</code>.
+Users requiring authoritative data should consult national standards
+bodies and the references cited in the database's comments.
+</p>
+
+<p>
+Errors in the <code><abbr>tz</abbr></code> database arise from many sources:
+</p>
+
+<ul>
+  <li>
+    The <code><abbr>tz</abbr></code> database predicts future
+    timestamps, and current predictions
+    will be incorrect after future governments change the rules.
+    For example, if today someone schedules a meeting for 13:00 next
+    October 1, Casablanca time, and tomorrow Morocco changes its
+    daylight saving rules, software can mess up after the rule change
+    if it blithely relies on conversions made before the change.
+  </li>
+  <li>
+    The pre-1970 entries in this database cover only a tiny sliver of how
+    clocks actually behaved; the vast majority of the necessary
+    information was lost or never recorded.
+    Thousands more timezones would be needed if
+    the <code><abbr>tz</abbr></code> database's scope were extended to
+    cover even just the known or guessed history of standard time; for
+    example, the current single entry for France would need to split
+    into dozens of entries, perhaps hundreds.
+    And in most of the world even this approach would be misleading
+    due to widespread disagreement or indifference about what times
+    should be observed.
+    In her 2015 book
+    <cite><a
+    href="https://www.hup.harvard.edu/catalog.php?isbn=9780674286146">The
+    Global Transformation of Time, 1870&ndash;1950</a></cite>,
+    Vanessa Ogle writes
+    "Outside of Europe and North America there was no system of time
+    zones at all, often not even a stable landscape of mean times,
+    prior to the middle decades of the twentieth century".
+    See: Timothy Shenk, <a
+href="https://www.dissentmagazine.org/blog/booked-a-global-history-of-time-vanessa-ogle">Booked:
+      A Global History of Time</a>. <cite>Dissent</cite> 2015-12-17.
+  </li>
+  <li>
+    Most of the pre-1970 data entries come from unreliable sources, often
+    astrology books that lack citations and whose compilers evidently
+    invented entries when the true facts were unknown, without
+    reporting which entries were known and which were invented.
+    These books often contradict each other or give implausible entries,
+    and on the rare occasions when they are checked they are
+    typically found to be incorrect.
+  </li>
+  <li>
+    For the UK the <code><abbr>tz</abbr></code> database relies on
+    years of first-class work done by
+    Joseph Myers and others; see
+    "<a href="https://www.polyomino.org.uk/british-time/">History of
+    legal time in Britain</a>".
+    Other countries are not done nearly as well.
+  </li>
+  <li>
+    Sometimes, different people in the same city maintain clocks
+    that differ significantly.
+    Historically, railway time was used by railroad companies (which
+    did not always
+    agree with each other), church-clock time was used for birth
+    certificates, etc.
+    More recently, competing political groups might disagree about
+    clock settings. Often this is merely common practice, but
+    sometimes it is set by law.
+    For example, from 1891 to 1911 the <abbr>UT</abbr> offset in France
+    was legally <abbr>UT</abbr> +00:09:21 outside train stations and
+    <abbr>UT</abbr> +00:04:21 inside. Other examples include
+    Chillicothe in 1920, Palm Springs in 1946/7, and Jerusalem and
+    Ürümqi to this day.
+  </li>
+  <li>
+    Although a named location in the <code><abbr>tz</abbr></code>
+    database stands for the containing region, its pre-1970 data
+    entries are often accurate for only a small subset of that region.
+    For example, <code>Europe/London</code> stands for the United
+    Kingdom, but its pre-1847 times are valid only for locations that
+    have London's exact meridian, and its 1847 transition
+    to <abbr>GMT</abbr> is known to be valid only for the L&amp;NW and
+    the Caledonian railways.
+  </li>
+  <li>
+    The <code><abbr>tz</abbr></code> database does not record the
+    earliest time for which a timezone's
+    data entries are thereafter valid for every location in the region.
+    For example, <code>Europe/London</code> is valid for all locations
+    in its region after <abbr>GMT</abbr> was made the standard time,
+    but the date of standardization (1880-08-02) is not in the
+    <code><abbr>tz</abbr></code> database, other than in commentary.
+    For many timezones the earliest time of
+    validity is unknown.
+  </li>
+  <li>
+    The <code><abbr>tz</abbr></code> database does not record a
+    region's boundaries, and in many cases the boundaries are not known.
+    For example, the timezone
+    <code>America/Kentucky/Louisville</code> represents a region
+    around the city of Louisville, the boundaries of which are
+    unclear.
+  </li>
+  <li>
+    Changes that are modeled as instantaneous transitions in the
+    <code><abbr>tz</abbr></code>
+    database were often spread out over hours, days, or even decades.
+  </li>
+  <li>
+    Even if the time is specified by law, locations sometimes
+    deliberately flout the law.
+  </li>
+  <li>
+    Early timekeeping practices, even assuming perfect clocks, were
+    often not specified to the accuracy that the
+    <code><abbr>tz</abbr></code> database requires.
+  </li>
+  <li>
+    The <code><abbr>tz</abbr></code> database cannot represent stopped clocks.
+    However, on 1911-03-11 at 00:00, some public-facing French clocks
+    were changed by stopping them for a few minutes to effect a transition.
+    The <code><abbr>tz</abbr></code> database models this via a
+    backward transition; the relevant French legislation does not
+    specify exactly how the transition was to occur.
+  </li>
+  <li>
+    Sometimes historical timekeeping was specified more precisely
+    than what the <code><abbr>tz</abbr></code> code can handle.
+    For example, from 1880 to 1916 clocks in Ireland observed Dublin Mean
+    Time (estimated to be <abbr>UT</abbr>
+    &minus;00:25:21.1); although the <code><abbr>tz</abbr></code>
+    source data can represent the .1 second, TZif files and the code cannot.
+    In practice these old specifications were rarely if ever
+    implemented to subsecond precision.
+  </li>
+  <li>
+    Even when all the timestamp transitions recorded by the
+    <code><abbr>tz</abbr></code> database are correct, the
+    <code><abbr>tz</abbr></code> rules that generate them may not
+    faithfully reflect the historical rules.
+    For example, from 1922 until World War II the UK moved clocks
+    forward the day following the third Saturday in April unless that
+    was Easter, in which case it moved clocks forward the previous
+    Sunday.
+    Because the <code><abbr>tz</abbr></code> database has no
+    way to specify Easter, these exceptional years are entered as
+    separate <code><abbr>tz</abbr> Rule</code> lines, even though the
+    legal rules did not change.
+    When transitions are known but the historical rules behind them are not,
+    the database contains <code>Zone</code> and <code>Rule</code>
+    entries that are intended to represent only the generated
+    transitions, not any underlying historical rules; however, this
+    intent is recorded at best only in commentary.
+  </li>
+  <li>
+    The <code><abbr>tz</abbr></code> database models time
+    using the <a
+    href="https://en.wikipedia.org/wiki/Proleptic_Gregorian_calendar">proleptic
+    Gregorian calendar</a> with days containing 24 equal-length hours
+    numbered 00 through 23, except when clock transitions occur.
+    Pre-standard time is modeled as local mean time.
+    However, historically many people used other calendars and other timescales.
+    For example, the Roman Empire used
+    the <a href="https://en.wikipedia.org/wiki/Julian_calendar">Julian
+    calendar</a>,
+    and <a href="https://en.wikipedia.org/wiki/Roman_timekeeping">Roman
+    timekeeping</a> had twelve varying-length daytime hours with a
+    non-hour-based system at night.
+    And even today, some local practices diverge from the Gregorian
+    calendar with 24-hour days. These divergences range from
+    relatively minor, such as Japanese bars giving times like "24:30" for the
+    wee hours of the morning, to more-significant differences such as <a
+    href="https://www.pri.org/stories/2015-01-30/if-you-have-meeting-ethiopia-you-better-double-check-time">the
+    east African practice of starting the day at dawn</a>, renumbering
+    the Western 06:00 to be 12:00. These practices are largely outside
+    the scope of the <code><abbr>tz</abbr></code> code and data, which
+    provide only limited support for date and time localization
+    such as that required by POSIX.
+    If <abbr>DST</abbr> is not used a different time zone
+    can often do the trick; for example, in Kenya a <code>TZ</code> setting
+    like <code>&lt;-03&gt;3</code> or <code>America/Cayenne</code> starts
+    the day six hours later than <code>Africa/Nairobi</code> does.
+  </li>
+  <li>
+    Early clocks were less reliable, and data entries do not represent
+    clock error.
+  </li>
+  <li>
+    The <code><abbr>tz</abbr></code> database assumes Universal Time
+    (<abbr>UT</abbr>) as an origin, even though <abbr>UT</abbr> is not
+    standardized for older timestamps.
+    In the <code><abbr>tz</abbr></code> database commentary,
+    <abbr>UT</abbr> denotes a family of time standards that includes
+    Coordinated Universal Time (<abbr>UTC</abbr>) along with other
+    variants such as <abbr>UT1</abbr> and <abbr>GMT</abbr>,
+    with days starting at midnight.
+    Although <abbr>UT</abbr> equals <abbr>UTC</abbr> for modern
+    timestamps, <abbr>UTC</abbr> was not defined until 1960, so
+    commentary uses the more-general abbreviation <abbr>UT</abbr> for
+    timestamps that might predate 1960.
+    Since <abbr>UT</abbr>, <abbr>UT1</abbr>, etc. disagree slightly,
+    and since pre-1972 <abbr>UTC</abbr> seconds varied in length,
+    interpretation of older timestamps can be problematic when
+    subsecond accuracy is needed.
+  </li>
+  <li>
+    Civil time was not based on atomic time before 1972, and we do not
+    know the history of
+    <a href="https://en.wikipedia.org/wiki/Earth's_rotation">earth's
+    rotation</a> accurately enough to map <a
+    href="https://en.wikipedia.org/wiki/International_System_of_Units"><abbr
+    title="International System of Units">SI</abbr></a> seconds to
+    historical <a href="https://en.wikipedia.org/wiki/Solar_time">solar time</a>
+    to more than about one-hour accuracy.
+    See: Stephenson FR, Morrison LV, Hohenkerk CY.
+    <a href="https://dx.doi.org/10.1098/rspa.2016.0404">Measurement of
+    the Earth's rotation: 720 BC to AD 2015</a>.
+    <cite>Proc Royal Soc A</cite>. 2016;472:20160404.
+    Also see: Espenak F. <a
+    href="https://eclipse.gsfc.nasa.gov/SEhelp/uncertainty2004.html">Uncertainty
+    in Delta T (ΔT)</a>.
+  </li>
+  <li>
+    The relationship between POSIX time (that is, <abbr>UTC</abbr> but
+    ignoring <a href="https://en.wikipedia.org/wiki/Leap_second">leap
+    seconds</a>) and <abbr>UTC</abbr> is not agreed upon after 1972.
+    Although the POSIX
+    clock officially stops during an inserted leap second, at least one
+    proposed standard has it jumping back a second instead; and in
+    practice POSIX clocks more typically either progress glacially during
+    a leap second, or are slightly slowed while near a leap second.
+  </li>
+  <li>
+    The <code><abbr>tz</abbr></code> database does not represent how
+    uncertain its information is.
+    Ideally it would contain information about when data entries are
+    incomplete or dicey.
+    Partial temporal knowledge is a field of active research, though,
+    and it is not clear how to apply it here.
+  </li>
+</ul>
+
+<p>
+In short, many, perhaps most, of the <code><abbr>tz</abbr></code>
+database's pre-1970 and future timestamps are either wrong or
+misleading.
+Any attempt to pass the
+<code><abbr>tz</abbr></code> database off as the definition of time
+should be unacceptable to anybody who cares about the facts.
+In particular, the <code><abbr>tz</abbr></code> database's
+<abbr>LMT</abbr> offsets should not be considered meaningful, and
+should not prompt creation of timezones
+merely because two locations
+differ in <abbr>LMT</abbr> or transitioned to standard time at
+different dates.
+</p>
+</section>
+
+<section>
+  <h2 id="functions">Time and date functions</h2>
+<p>
+The <code><abbr>tz</abbr></code> code contains time and date functions
+that are upwards compatible with those of POSIX.
+Code compatible with this package is already
+<a href="tz-link.html#tzdb">part of many platforms</a>, where the
+primary use of this package is to update obsolete time-related files.
+To do this, you may need to compile the time zone compiler
+'<code>zic</code>' supplied with this package instead of using the
+system '<code>zic</code>', since the format of <code>zic</code>'s
+input is occasionally extended, and a platform may still be shipping
+an older <code>zic</code>.
+</p>
+
+<h3 id="POSIX">POSIX properties and limitations</h3>
+<ul>
+  <li>
+    <p>
+    In POSIX, time display in a process is controlled by the
+    environment variable <code>TZ</code>.
+    Unfortunately, the POSIX
+    <code>TZ</code> string takes a form that is hard to describe and
+    is error-prone in practice.
+    Also, POSIX <code>TZ</code> strings cannot deal with daylight
+    saving time rules not based on the Gregorian calendar (as in
+    Iran), or with situations where more than two time zone
+    abbreviations or <abbr>UT</abbr> offsets are used in an area.
+    </p>
+
+    <p>
+    The POSIX <code>TZ</code> string takes the following form:
+    </p>
+
+    <p>
+    <var>stdoffset</var>[<var>dst</var>[<var>offset</var>][<code>,</code><var>date</var>[<code>/</code><var>time</var>]<code>,</code><var>date</var>[<code>/</code><var>time</var>]]]
+    </p>
+
+    <p>
+    where:
+    </p>
+
+    <dl>
+      <dt><var>std</var> and <var>dst</var></dt><dd>
+	are 3 or more characters specifying the standard
+	and daylight saving time (<abbr>DST</abbr>) zone abbreviations.
+	Starting with POSIX.1-2001, <var>std</var> and <var>dst</var>
+	may also be in a quoted form like '<code>&lt;+09&gt;</code>';
+	this allows "<code>+</code>" and "<code>-</code>" in the names.
+      </dd>
+      <dt><var>offset</var></dt><dd>
+	is of the form
+	'<code>[&plusmn;]<var>hh</var>:[<var>mm</var>[:<var>ss</var>]]</code>'
+	and specifies the offset west of <abbr>UT</abbr>.
+	'<var>hh</var>' may be a single digit;
+	0&le;<var>hh</var>&le;24.
+	The default <abbr>DST</abbr> offset is one hour ahead of
+	standard time.
+      </dd>
+      <dt><var>date</var>[<code>/</code><var>time</var>]<code>,</code><var>date</var>[<code>/</code><var>time</var>]</dt><dd>
+	specifies the beginning and end of <abbr>DST</abbr>.
+	If this is absent, the system supplies its own ruleset
+	for <abbr>DST</abbr>, and its rules can differ from year to year;
+	typically <abbr>US</abbr> <abbr>DST</abbr> rules are used.
+      </dd>
+      <dt><var>time</var></dt><dd>
+	takes the form
+	'<var>hh</var><code>:</code>[<var>mm</var>[<code>:</code><var>ss</var>]]'
+	and defaults to 02:00.
+	This is the same format as the offset, except that a
+	leading '<code>+</code>' or '<code>-</code>' is not allowed.
+      </dd>
+      <dt><var>date</var></dt><dd>
+	takes one of the following forms:
+	<dl>
+	  <dt>J<var>n</var> (1&le;<var>n</var>&le;365)</dt><dd>
+	    origin-1 day number not counting February 29
+	  </dd>
+	  <dt><var>n</var> (0&le;<var>n</var>&le;365)</dt><dd>
+	    origin-0 day number counting February 29 if present
+	  </dd>
+	  <dt><code>M</code><var>m</var><code>.</code><var>n</var><code>.</code><var>d</var>
+	    (0[Sunday]&le;<var>d</var>&le;6[Saturday], 1&le;<var>n</var>&le;5,
+	    1&le;<var>m</var>&le;12)</dt><dd>
+	    for the <var>d</var>th day of week <var>n</var> of
+	    month <var>m</var> of the year, where week 1 is the first
+	    week in which day <var>d</var> appears, and
+	    '<code>5</code>' stands for the last week in which
+	    day <var>d</var> appears (which may be either the 4th or
+	    5th week).
+	    Typically, this is the only useful form; the <var>n</var>
+	    and <code>J</code><var>n</var> forms are rarely used.
+	  </dd>
+	</dl>
+      </dd>
+    </dl>
+
+    <p>
+    Here is an example POSIX <code>TZ</code> string for New
+    Zealand after 2007.
+    It says that standard time (<abbr>NZST</abbr>) is 12 hours ahead
+    of <abbr>UT</abbr>, and that daylight saving time
+    (<abbr>NZDT</abbr>) is observed from September's last Sunday at
+    02:00 until April's first Sunday at 03:00:
+    </p>
+
+    <pre><code>TZ='NZST-12NZDT,M9.5.0,M4.1.0/3'</code></pre>
+
+    <p>
+    This POSIX <code>TZ</code> string is hard to remember, and
+    mishandles some timestamps before 2008.
+    With this package you can use this instead:
+    </p>
+
+    <pre><code>TZ='Pacific/Auckland'</code></pre>
+  </li>
+  <li>
+    POSIX does not define the <abbr>DST</abbr> transitions
+    for <code>TZ</code> values like
+    "<code>EST5EDT</code>".
+    Traditionally the current <abbr>US</abbr> <abbr>DST</abbr> rules
+    were used to interpret such values, but this meant that the
+    <abbr>US</abbr> <abbr>DST</abbr> rules were compiled into each
+    program that did time conversion. This meant that when
+    <abbr>US</abbr> time conversion rules changed (as in the United
+    States in 1987), all programs that did time conversion had to be
+    recompiled to ensure proper results.
+  </li>
+  <li>
+    The <code>TZ</code> environment variable is process-global, which
+    makes it hard to write efficient, thread-safe applications that
+    need access to multiple timezones.
+  </li>
+  <li>
+    In POSIX, there is no tamper-proof way for a process to learn the
+    system's best idea of local (wall clock) time.
+    This is important for applications that an administrator wants
+    used only at certain times &ndash; without regard to whether the
+    user has fiddled the
+    <code>TZ</code> environment variable.
+    While an administrator can "do everything in <abbr>UT</abbr>" to
+    get around the problem, doing so is inconvenient and precludes
+    handling daylight saving time shifts &ndash; as might be required to
+    limit phone calls to off-peak hours.
+  </li>
+  <li>
+    POSIX provides no convenient and efficient way to determine
+    the <abbr>UT</abbr> offset and time zone abbreviation of arbitrary
+    timestamps, particularly for timezones
+    that do not fit into the POSIX model.
+  </li>
+  <li>
+    POSIX requires that <code>time_t</code> clock counts exclude leap
+    seconds.
+  </li>
+  <li>
+    The <code><abbr>tz</abbr></code> code attempts to support all the
+    <code>time_t</code> implementations allowed by POSIX.
+    The <code>time_t</code> type represents a nonnegative count of seconds
+    since 1970-01-01 00:00:00 <abbr>UTC</abbr>, ignoring leap seconds.
+    In practice, <code>time_t</code> is usually a signed 64- or 32-bit
+    integer; 32-bit signed <code>time_t</code> values stop working after
+    2038-01-19 03:14:07 <abbr>UTC</abbr>, so new implementations these
+    days typically use a signed 64-bit integer.
+    Unsigned 32-bit integers are used on one or two platforms, and 36-bit
+    and 40-bit integers are also used occasionally.
+    Although earlier POSIX versions allowed <code>time_t</code> to be a
+    floating-point type, this was not supported by any practical system,
+    and POSIX.1-2013 and the <code><abbr>tz</abbr></code> code both
+    require <code>time_t</code> to be an integer type.
+  </li>
+</ul>
+
+<h3 id="POSIX-extensions">Extensions to POSIX in the
+<code><abbr>tz</abbr></code> code</h3>
+<ul>
+  <li>
+    <p>
+    The <code>TZ</code> environment variable is used in generating
+    the name of a file from which time-related information is read
+    (or is interpreted à la POSIX); <code>TZ</code> is no longer
+    constrained to be a string containing abbreviations
+    and numeric data as described <a href="#POSIX">above</a>.
+    The file's format is <dfn><abbr>TZif</abbr></dfn>,
+    a timezone information format that contains binary data; see
+    <a href="https://datatracker.ietf.org/doc/html/8536">Internet
+    <abbr>RFC</abbr> 8536</a>.
+    The daylight saving time rules to be used for a
+    particular timezone are encoded in the
+    <abbr>TZif</abbr> file; the format of the file allows <abbr>US</abbr>,
+    Australian, and other rules to be encoded, and
+    allows for situations where more than two time zone
+    abbreviations are used.
+    </p>
+    <p>
+    It was recognized that allowing the <code>TZ</code> environment
+    variable to take on values such as '<code>America/New_York</code>'
+    might cause "old" programs (that expect <code>TZ</code> to have a
+    certain form) to operate incorrectly; consideration was given to using
+    some other environment variable (for example, <code>TIMEZONE</code>)
+    to hold the string used to generate the <abbr>TZif</abbr> file's name.
+    In the end, however, it was decided to continue using
+    <code>TZ</code>: it is widely used for time zone purposes;
+    separately maintaining both <code>TZ</code>
+    and <code>TIMEZONE</code> seemed a nuisance; and systems where
+    "new" forms of <code>TZ</code> might cause problems can simply
+    use legacy <code>TZ</code> values such as "<code>EST5EDT</code>" which
+    can be used by "new" programs as well as by "old" programs that
+    assume pre-POSIX <code>TZ</code> values.
+    </p>
+  </li>
+  <li>
+    The code supports platforms with a <abbr>UT</abbr> offset member
+    in <code>struct tm</code>, e.g., <code>tm_gmtoff</code>,
+    or with a time zone abbreviation member in
+    <code>struct tm</code>, e.g., <code>tm_zone</code>. As noted
+    in <a href="https://austingroupbugs.net/view.php?id=1533">Austin
+    Group defect 1533</a>, a future version of POSIX is planned to
+    require <code>tm_gmtoff</code> and <code>tm_zone</code>.
+  </li>
+  <li>
+    Functions <code>tzalloc</code>, <code>tzfree</code>,
+    <code>localtime_rz</code>, and <code>mktime_z</code> for
+    more-efficient thread-safe applications that need to use multiple
+    timezones.
+    The <code>tzalloc</code> and <code>tzfree</code> functions
+    allocate and free objects of type <code>timezone_t</code>,
+    and <code>localtime_rz</code> and <code>mktime_z</code> are
+    like <code>localtime_r</code> and <code>mktime</code> with an
+    extra <code>timezone_t</code> argument.
+    The functions were inspired by <a href="https://netbsd.org/">NetBSD</a>.
+  </li>
+  <li>
+    Negative <code>time_t</code> values are supported, on systems
+    where <code>time_t</code> is signed.
+  </li>
+  <li>
+    These functions can account for leap seconds;
+    see <a href="#leapsec">Leap seconds</a> below.
+  </li>
+</ul>
+
+<h3 id="vestigial">POSIX features no longer needed</h3>
+<p>
+POSIX and <a href="https://en.wikipedia.org/wiki/ISO_C"><abbr>ISO</abbr> C</a>
+define some <a href="https://en.wikipedia.org/wiki/API"><abbr
+title="application programming interface">API</abbr>s</a> that are vestigial:
+they are not needed, and are relics of a too-simple model that does
+not suffice to handle many real-world timestamps.
+Although the <code><abbr>tz</abbr></code> code supports these
+vestigial <abbr>API</abbr>s for backwards compatibility, they should
+be avoided in portable applications.
+The vestigial <abbr>API</abbr>s are:
+</p>
+<ul>
+  <li>
+    The POSIX <code>tzname</code> variable does not suffice and is no
+    longer needed.
+    To get a timestamp's time zone abbreviation, consult
+    the <code>tm_zone</code> member if available; otherwise,
+    use <code>strftime</code>'s <code>"%Z"</code> conversion
+    specification.
+  </li>
+  <li>
+    The POSIX <code>daylight</code> and <code>timezone</code>
+    variables do not suffice and are no longer needed.
+    To get a timestamp's <abbr>UT</abbr> offset, consult
+    the <code>tm_gmtoff</code> member if available; otherwise,
+    subtract values returned by <code>localtime</code>
+    and <code>gmtime</code> using the rules of the Gregorian calendar,
+    or use <code>strftime</code>'s <code>"%z"</code> conversion
+    specification if a string like <code>"+0900"</code> suffices.
+  </li>
+  <li>
+    The <code>tm_isdst</code> member is almost never needed and most of
+    its uses should be discouraged in favor of the abovementioned
+    <abbr>API</abbr>s.
+    Although it can still be used in arguments to
+    <code>mktime</code> to disambiguate timestamps near
+    a <abbr>DST</abbr> transition when the clock jumps back on
+    platforms lacking <code>tm_gmtoff</code>, this
+    disambiguation does not work when standard time itself jumps back,
+    which can occur when a location changes to a time zone with a
+    lesser <abbr>UT</abbr> offset.
+  </li>
+</ul>
+
+<h3 id="other-portability">Other portability notes</h3>
+<ul>
+  <li>
+    The <a href="https://en.wikipedia.org/wiki/Version_7_Unix">7th Edition
+    UNIX</a> <code>timezone</code> function is not present in this
+    package; it is impossible to reliably map <code>timezone</code>'s
+    arguments (a "minutes west of <abbr>GMT</abbr>" value and a
+    "daylight saving time in effect" flag) to a time zone
+    abbreviation, and we refuse to guess.
+    Programs that in the past used the <code>timezone</code> function
+    may now examine <code>localtime(&amp;clock)-&gt;tm_zone</code>
+    (if <code>TM_ZONE</code> is defined) or
+    <code>tzname[localtime(&amp;clock)-&gt;tm_isdst]</code>
+    (if <code>HAVE_TZNAME</code> is nonzero) to learn the correct time
+    zone abbreviation to use.
+  </li>
+  <li>
+    The <a
+    href="https://en.wikipedia.org/wiki/History_of_the_Berkeley_Software_Distribution#4.2BSD"><abbr>4.2BSD</abbr></a>
+    <code>gettimeofday</code> function is not
+    used in this package.
+    This formerly let users obtain the current <abbr>UTC</abbr> offset
+    and <abbr>DST</abbr> flag, but this functionality was removed in
+    later versions of <abbr>BSD</abbr>.
+  </li>
+  <li>
+    In <abbr>SVR2</abbr>, time conversion fails for near-minimum or
+    near-maximum <code>time_t</code> values when doing conversions
+    for places that do not use <abbr>UT</abbr>.
+    This package takes care to do these conversions correctly.
+    A comment in the source code tells how to get compatibly wrong
+    results.
+  </li>
+  <li>
+    The functions that are conditionally compiled
+    if <code>STD_INSPIRED</code> is defined should, at this point, be
+    looked on primarily as food for thought.
+    They are not in any sense "standard compatible" &ndash; some are
+    not, in fact, specified in <em>any</em> standard.
+    They do, however, represent responses of various authors to
+    standardization proposals.
+  </li>
+  <li>
+    Other time conversion proposals, in particular those supported by the
+    <a href="https://howardhinnant.github.io/date/tz.html">Time Zone
+    Database Parser</a>, offer a wider selection of functions
+    that provide capabilities beyond those provided here.
+    The absence of such functions from this package is not meant to
+    discourage the development, standardization, or use of such
+    functions.
+    Rather, their absence reflects the decision to make this package
+    contain valid extensions to POSIX, to ensure its broad
+    acceptability.
+    If more powerful time conversion functions can be standardized, so
+    much the better.
+  </li>
+</ul>
+</section>
+
+<section>
+  <h2 id="stability">Interface stability</h2>
+<p>
+The <code><abbr>tz</abbr></code> code and data supply the following interfaces:
+</p>
+
+<ul>
+  <li>
+    A set of timezone names as per
+      "<a href="#naming">Timezone identifiers</a>" above.
+  </li>
+  <li>
+    Library functions described in "<a href="#functions">Time and date
+      functions</a>" above.
+  </li>
+  <li>
+    The programs <code>tzselect</code>, <code>zdump</code>,
+    and <code>zic</code>, documented in their man pages.
+  </li>
+  <li>
+    The format of <code>zic</code> input files, documented in
+    the <code>zic</code> man page.
+  </li>
+  <li>
+    The format of <code>zic</code> output files, documented in
+    the <code>tzfile</code> man page.
+  </li>
+  <li>
+    The format of zone table files, documented in <code>zone1970.tab</code>.
+  </li>
+  <li>
+    The format of the country code file, documented in <code>iso3166.tab</code>.
+  </li>
+  <li>
+    The version number of the code and data, as the first line of
+    the text file '<code>version</code>' in each release.
+  </li>
+</ul>
+
+<p>
+Interface changes in a release attempt to preserve compatibility with
+recent releases.
+For example, <code><abbr>tz</abbr></code> data files typically do not
+rely on recently-added <code>zic</code> features, so that users can
+run older <code>zic</code> versions to process newer data files.
+<a href="tz-link.html#download">Downloading
+the <code><abbr>tz</abbr></code> database</a> describes how releases
+are tagged and distributed.
+</p>
+
+<p>
+Interfaces not listed above are less stable.
+For example, users should not rely on particular <abbr>UT</abbr>
+offsets or abbreviations for timestamps, as data entries are often
+based on guesswork and these guesses may be corrected or improved.
+</p>
+
+<p>
+Timezone boundaries are not part of the stable interface.
+For example, even though the <samp>Asia/Bangkok</samp> timezone
+currently includes Chang Mai, Hanoi, and Phnom Penh, this is not part
+of the stable interface and the timezone can split at any time.
+If a calendar application records a future event in some location other
+than Bangkok by putting "<samp>Asia/Bangkok</samp>" in the event's record,
+the application should be robust in the presence of timezone splits
+between now and the future time.
+</p>
+</section>
+
+<section>
+  <h2 id="leapsec">Leap seconds</h2>
+<p>
+The <code><abbr>tz</abbr></code> code and data can account for leap seconds,
+thanks to code contributed by Bradley White.
+However, the leap second support of this package is rarely used directly
+because POSIX requires leap seconds to be excluded and many
+software packages would mishandle leap seconds if they were present.
+Instead, leap seconds are more commonly handled by occasionally adjusting
+the operating system kernel clock as described in
+<a href="tz-link.html#precision">Precision timekeeping</a>,
+and this package by default installs a <samp>leapseconds</samp> file
+commonly used by
+<a href="https://www.ntp.org"><abbr title="Network Time Protocol">NTP</abbr></a>
+software that adjusts the kernel clock.
+However, kernel-clock twiddling approximates UTC only roughly,
+and systems needing more-precise UTC can use this package's leap
+second support directly.
+</p>
+
+<p>
+The directly-supported mechanism assumes that <code>time_t</code>
+counts of seconds since the POSIX epoch normally include leap seconds,
+as opposed to POSIX <code>time_t</code> counts which exclude leap seconds.
+This modified timescale is converted to <abbr>UTC</abbr>
+at the same point that time zone and <abbr>DST</abbr>
+adjustments are applied &ndash;
+namely, at calls to <code>localtime</code> and analogous functions &ndash;
+and the process is driven by leap second information
+stored in alternate versions of the <abbr>TZif</abbr> files.
+Because a leap second adjustment may be needed even
+if no time zone correction is desired,
+calls to <code>gmtime</code>-like functions
+also need to consult a <abbr>TZif</abbr> file,
+conventionally named <samp><abbr>Etc/UTC</abbr></samp>
+(<samp><abbr>GMT</abbr></samp> in previous versions),
+to see whether leap second corrections are needed.
+To convert an application's <code>time_t</code> timestamps to or from
+POSIX <code>time_t</code> timestamps (for use when, say,
+embedding or interpreting timestamps in portable
+<a href="https://en.wikipedia.org/wiki/Tar_(computing)"><code>tar</code></a>
+files),
+the application can call the utility functions
+<code>time2posix</code> and <code>posix2time</code>
+included with this package.
+</p>
+
+<p>
+If the POSIX-compatible <abbr>TZif</abbr> file set is installed
+in a directory whose basename is <samp>zoneinfo</samp>, the
+leap-second-aware file set is by default installed in a separate
+directory <samp>zoneinfo-leaps</samp>.
+Although each process can have its own time zone by setting
+its <code>TZ</code> environment variable, there is no support for some
+processes being leap-second aware while other processes are
+POSIX-compatible; the leap-second choice is system-wide.
+So if you configure your kernel to count leap seconds, you should also
+discard <samp>zoneinfo</samp> and rename <samp>zoneinfo-leaps</samp>
+to <samp>zoneinfo</samp>.
+Alternatively, you can install just one set of <abbr>TZif</abbr> files
+in the first place; see the <code>REDO</code> variable in this package's
+<a href="https://en.wikipedia.org/wiki/Makefile">makefile</a>.
+</p>
+</section>
+
+<section>
+  <h2 id="calendar">Calendrical issues</h2>
+<p>
+Calendrical issues are a bit out of scope for a time zone database,
+but they indicate the sort of problems that we would run into if we
+extended the time zone database further into the past.
+An excellent resource in this area is Edward M. Reingold
+and Nachum Dershowitz, <cite><a
+href="https://www.cambridge.org/fr/academic/subjects/computer-science/computing-general-interest/calendrical-calculations-ultimate-edition-4th-edition">Calendrical
+Calculations: The Ultimate Edition</a></cite>, Cambridge University Press (2018).
+Other information and sources are given in the file '<code>calendars</code>'
+in the <code><abbr>tz</abbr></code> distribution.
+They sometimes disagree.
+</p>
+</section>
+
+<section>
+  <h2 id="planets">Time and time zones on other planets</h2>
+<p>
+Some people's work schedules have used
+<a href="https://en.wikipedia.org/wiki/Timekeeping_on_Mars">Mars time</a>.
+Jet Propulsion Laboratory (JPL) coordinators kept Mars time on
+and off during the
+<a href="https://en.wikipedia.org/wiki/Mars_Pathfinder">Mars
+Pathfinder</a> mission (1997).
+Some of their family members also adapted to Mars time.
+Dozens of special Mars watches were built for JPL workers who kept
+Mars time during the
+<a href="https://en.wikipedia.org/wiki/Mars_Exploration_Rover">Mars
+Exploration Rovers (MER)</a> mission (2004&ndash;2018).
+These timepieces looked like normal Seikos and Citizens but were adjusted
+to use Mars seconds rather than terrestrial seconds, although
+unfortunately the adjusted watches were unreliable and appear to have
+had only limited use.
+</p>
+
+<p>
+A Mars solar day is called a "sol" and has a mean period equal to
+about 24 hours 39 minutes 35.244 seconds in terrestrial time.
+It is divided into a conventional 24-hour clock, so each Mars second
+equals about 1.02749125 terrestrial seconds.
+(One MER worker noted, "If I am working Mars hours, and Mars hours are
+2.5% more than Earth hours, shouldn't I get an extra 2.5% pay raise?")
+</p>
+
+<p>
+The <a href="https://en.wikipedia.org/wiki/Prime_meridian">prime
+meridian</a> of Mars goes through the center of the crater
+<a href="https://en.wikipedia.org/wiki/Airy-0">Airy-0</a>, named in
+honor of the British astronomer who built the Greenwich telescope that
+defines Earth's prime meridian.
+Mean solar time on the Mars prime meridian is
+called Mars Coordinated Time (<abbr>MTC</abbr>).
+</p>
+
+<p>
+Each landed mission on Mars has adopted a different reference for
+solar timekeeping, so there is no real standard for Mars time zones.
+For example, the MER mission defined two time zones "Local
+Solar Time A" and "Local Solar Time B" for its two missions, each zone
+designed so that its time equals local true solar time at
+approximately the middle of the nominal mission.
+The A and B zones differ enough so that an MER worker assigned to
+the A zone might suffer "Mars lag" when switching to work in the B zone.
+Such a "time zone" is not particularly suited for any application
+other than the mission itself.
+</p>
+
+<p>
+Many calendars have been proposed for Mars, but none have achieved
+wide acceptance.
+Astronomers often use Mars Sol Date (<abbr>MSD</abbr>) which is a
+sequential count of Mars solar days elapsed since about 1873-12-29
+12:00 <abbr>GMT</abbr>.
+</p>
+
+<p>
+In our solar system, Mars is the planet with time and calendar most
+like Earth's.
+On other planets, Sun-based time and calendars would work quite
+differently.
+For example, although Mercury's
+<a href="https://en.wikipedia.org/wiki/Rotation_period">sidereal
+rotation period</a> is 58.646 Earth days, Mercury revolves around the
+Sun so rapidly that an observer on Mercury's equator would see a
+sunrise only every 175.97 Earth days, i.e., a Mercury year is 0.5 of a
+Mercury day.
+Venus is more complicated, partly because its rotation is slightly
+<a href="https://en.wikipedia.org/wiki/Retrograde_motion">retrograde</a>:
+its year is 1.92 of its days.
+Gas giants like Jupiter are trickier still, as their polar and
+equatorial regions rotate at different rates, so that the length of a
+day depends on latitude.
+This effect is most pronounced on Neptune, where the day is about 12
+hours at the poles and 18 hours at the equator.
+</p>
+
+<p>
+Although the <code><abbr>tz</abbr></code> database does not support
+time on other planets, it is documented here in the hopes that support
+will be added eventually.
+</p>
+
+<p>
+Sources for time on other planets:
+</p>
+
+<ul>
+  <li>
+    Michael Allison and Robert Schmunk,
+    "<a href="https://www.giss.nasa.gov/tools/mars24/help/notes.html">Technical
+      Notes on Mars Solar Time as Adopted by the Mars24 Sunclock</a>"
+    (2020-03-08).
+  </li>
+  <li>
+    Zara Mirmalek,
+    <em><a href="https://mitpress.mit.edu/books/making-time-mars">Making
+	Time on Mars</a></em>, MIT Press (March 2020), ISBN 978-0262043854.
+  </li>
+  <li>
+    Jia-Rui Chong,
+    "<a href="https://www.latimes.com/archives/la-xpm-2004-jan-14-sci-marstime14-story.html">Workdays
+    Fit for a Martian</a>", <cite>Los Angeles Times</cite>
+    (2004-01-14), pp A1, A20&ndash;A21.
+  </li>
+  <li>
+    Tom Chmielewski,
+    "<a href="https://www.theatlantic.com/technology/archive/2015/02/jet-lag-is-worse-on-mars/386033/">Jet
+    Lag Is Worse on Mars</a>", <cite>The Atlantic</cite> (2015-02-26)
+  </li>
+  <li>
+    Matt Williams,
+    "<a href="https://www.universetoday.com/37481/days-of-the-planets/">How
+    long is a day on the other planets of the solar system?</a>"
+    (2016-01-20).
+  </li>
+</ul>
+</section>
+
+<footer>
+  <hr>
+  This file is in the public domain, so clarified as of 2009-05-17 by
+  Arthur David Olson.
+</footer>
+</body>
+</html>
diff --git a/contrib/tzcode/stdtime/time2posix.3 b/contrib/tzcode/time2posix.3
index 1a1ec95699f9..6959c890a65b 100644
--- a/contrib/tzcode/stdtime/time2posix.3
+++ b/contrib/tzcode/time2posix.3
@@ -1,6 +1,9 @@
+.\" This file is in the public domain, so clarified as of
+.\" 1996-06-05 by Arthur David Olson.
+.\"
 .\" $FreeBSD$
 .\"
-.Dd September 11, 2005
+.Dd December 15, 2022
 .Dt TIME2POSIX 3
 .Os
 .Sh NAME
@@ -17,9 +20,10 @@
 .Fn posix2time "time_t t"
 .Sh DESCRIPTION
 .St -p1003.1-88
-legislates that a time_t value of
-536457599 shall correspond to "Wed Dec 31 23:59:59 GMT 1986."
-This effectively implies that POSIX time_t's cannot include leap
+requires the time_t value 536457599 to stand for 1986-12-31 23:59:59 UTC.
+This effectively implies that POSIX
+.Vt time_t
+values cannot include leap
 seconds and,
 therefore,
 that the system time must be adjusted as each leap occurs.
@@ -28,15 +32,22 @@ If the time package is configured with leap-second support
 enabled,
 however,
 no such adjustment is needed and
-time_t values continue to increase over leap events
-(as a true `seconds since...' value).
+.Vt time_t
+values continue to increase over leap events
+(as a true
+.Dq "seconds since..."
+value).
 This means that these values will differ from those required by POSIX
 by the net number of leap seconds inserted since the Epoch.
 .Pp
-Typically this is not a problem as the type time_t is intended
+Typically this is not a problem as the type
+.Vt time_t
+is intended
 to be
 (mostly)
-opaque\(emtime_t values should only be obtained-from and
+opaque \(em
+.Vt time_t
+values should only be obtained-from and
 passed-to functions such as
 .Xr time 3 ,
 .Xr localtime 3 ,
@@ -46,11 +57,15 @@ and
 However,
 .St -p1003.1-88
 gives an arithmetic
-expression for directly computing a time_t value from a given date/time,
+expression for directly computing a
+.Vt time_t
+value from a given date/time,
 and the same relationship is assumed by some
 (usually older)
 applications.
-Any programs creating/dissecting time_t's
+Any programs creating/dissecting
+.Vt time_t
+values
 using such a relationship will typically not handle intervals
 over leap seconds correctly.
 .Pp
@@ -58,8 +73,12 @@ The
 .Fn time2posix
 and
 .Fn posix2time
-functions are provided to address this time_t mismatch by converting
-between local time_t values and their POSIX equivalents.
+functions are provided to address this
+.Vt time_t
+mismatch by converting
+between local
+.Vt time_t
+values and their POSIX equivalents.
 This is done by accounting for the number of time-base changes that
 would have taken place on a POSIX system as leap seconds were inserted
 or deleted.
@@ -69,21 +88,27 @@ or when communicating with POSIX-compliant systems.
 .Pp
 The
 .Fn time2posix
-function is single-valued.
+function
+is single-valued.
 That is,
-every local time_t
-corresponds to a single POSIX time_t.
+every local
+.Vt time_t
+corresponds to a single POSIX
+.Vt time_t .
 The
 .Fn posix2time
-function is less well-behaved:
+function
+is less well-behaved:
 for a positive leap second hit the result is not unique,
 and for a negative leap second hit the corresponding
-POSIX time_t does not exist so an adjacent value is returned.
+POSIX
+.Vt time_t
+does not exist so an adjacent value is returned.
 Both of these are good indicators of the inferiority of the
 POSIX representation.
 .Pp
-The following table summarizes the relationship between time_t
-and its conversion to,
+The following table summarizes the relationship between a time
+T and its conversion to,
 and back from,
 the POSIX representation over the leap second inserted at the end of June,
 1993.
@@ -106,8 +131,12 @@ A leap second deletion would look like...
 .D1 No "[Note: posix2time(B+1) => A+0 or A+1]"
 .Pp
 If leap-second support is not enabled,
-local time_t's and
-POSIX time_t's are equivalent,
+local
+.Vt time_t
+and
+POSIX
+.Vt time_t
+values are equivalent,
 and both
 .Fn time2posix
 and
@@ -118,6 +147,3 @@ degenerate to the identity function.
 .Xr localtime 3 ,
 .Xr mktime 3 ,
 .Xr time 3
-.\" @(#)time2posix.3  8.2
-.\" This file is in the public domain, so clarified as of
-.\" 1996-06-05 by Arthur David Olson.
diff --git a/contrib/tzcode/tz-art.html b/contrib/tzcode/tz-art.html
new file mode 100644
index 000000000000..567953415f63
--- /dev/null
+++ b/contrib/tzcode/tz-art.html
@@ -0,0 +1,636 @@
+<!DOCTYPE html>
+<html lang="en">
+<head>
+<meta charset="UTF-8">
+<title>Time and the Arts</title>
+</head>
+<body>
+<h1>Time and the Arts</h1>
+<h2>Documentaries</h2>
+<ul>
+<li>
+"<a href="https://www.youtube.com/watch?v=84aWtseb2-4">Daylight
+Saving Time Explained</a>" (2011; 6:39) lightly covers daylight saving
+time's theory, history, pros and cons. Among other things, it explains
+Arizona's daylight-saving enclaves quite well.</li>
+<li>
+"<a href="https://www.youtube.com/watch?v=-5wpm-gesOY">The Problem
+with Time &amp; Timezones &ndash; Computerphile</a>" (2013; 10:12) delves
+into problems that programmers have with timekeeping.</li>
+<li>
+"<a href="https://www.rferl.org/a/28375932.html">All The Time In The World:
+Explaining The Mysteries Of Time Zones</a>" (2017; 2:15)
+briefly says why France has more time zones than Russia.
+<li>
+"<a href="https://www.youtube.com/watch?v=yRz-Dl60Lfc">Why Denmark is
+.17 Seconds Behind The World</a>" (2019; 6:29) explains why Denmark and
+the United Kingdom don't exactly follow their own law about civil time.
+<li>
+"About Time" (1962; 59 minutes) is part of the
+Bell Science extravaganza, with Frank Baxter, Richard Deacon, and Les Tremayne.
+Its advisor was Richard Feynman, and it was voiced by Mel Blanc.
+(<a href="https://www.imdb.com/title/tt0154110/">IMDb entry</a>.)</li>
+</ul>
+<h2>Movies</h2>
+<ul>
+<li>
+In the 1946 movie <em>A Matter of Life and Death</em>
+(U.S. title <em>Stairway to Heaven</em>)
+there is a reference to British Double Summer Time.
+The time does not play a large part in the plot;
+it's just a passing reference to the time when one of the
+characters was supposed to have died (but didn't).
+(<a href="https://www.imdb.com/title/tt0038733/">IMDb entry.</a>)
+(Dave Cantor)
+<li>
+The 1953 railway comedy movie <em>The Titfield Thunderbolt</em> includes a
+play on words on British Double Summer Time. Valentine's wife wants
+him to leave the pub and asks him, "Do you know what time it is?"
+And he, happy where he is, replies: "Yes, my love. Summer double time."
+(<a href="https://www.imdb.com/title/tt0046436/">IMDb entry.</a>)
+(Mark Brader, 2009-10-02)
+</li>
+<li>
+The premise of the 1999 caper movie <em>Entrapment</em> involves computers
+in an international banking network being shut down briefly at
+midnight in each time zone to avoid any problems at the transition
+from the year 1999 to 2000 in that zone. (Hmmmm.) If this shutdown
+is extended by 10 seconds, it will create a one-time opportunity for
+a gigantic computerized theft. To achieve this, at one location the
+crooks interfere with the microwave system supplying time signals to
+the computer, advancing the time by 0.1 second each minute over the
+last hour of 1999. (So this movie teaches us that 0.1 &times; 60 = 10.)
+(<a href="https://www.imdb.com/title/tt0137494/">IMDb entry.</a>)
+(Mark Brader, 2009-10-02)
+</li>
+<li>
+One mustn't forget the
+<a href="https://www.youtube.com/watch?v=k4EUTMPuvHo">trailer</a>
+(2014; 2:23) for the movie <em>Daylight Saving</em>.
+</li>
+</ul>
+<h2>TV episodes</h2>
+<ul>
+<li>
+An episode of <em>The Adventures of Superman</em> entitled "The Mysterious
+Cube," first aired 1958-02-24, had Superman convincing the controllers
+of the Arlington Time Signal to broadcast ahead of actual time;
+doing so got a crook trying to be declared dead to
+emerge a bit too early from the titular enclosure.
+(<a href="https://www.imdb.com/title/tt0506628/">IMDb entry</a>.)
+</li>
+<li>
+"<a href="https://en.wikipedia.org/wiki/The_Chimes_of_Big_Ben">The Chimes
+of Big Ben</a>", <em>The Prisoner</em>, episode 2, ITC, 1967-10-06.
+Our protagonist tumbles to
+the fraudulent nature of a Poland-to-England escape upon hearing "Big
+Ben" chiming on Polish local time.
+(<a href="https://www.imdb.com/title/tt0679185/">IMDb entry.</a>)
+</li>
+<li>
+"The Susie", <em>Seinfeld</em>, season 8, episode 15, NBC, 1997-02-13.
+Kramer decides that daylight saving time
+isn't coming fast enough, so he sets his watch ahead an hour.
+</li>
+<li>
+"20 Hours in America", <em>The West Wing</em>, season 4, episodes 1&ndash;2,
+2002-09-25, contained a <a
+href="https://www.youtube.com/watch?v=-J1NHzQ1sgc">scene</a> that
+saw White House staffers stranded in Indiana; they thought they had time to
+catch Air Force One but were done in by intra-Indiana local time changes.
+</li>
+<li>
+"In what time zone would you find New York City?" was a $200 question on
+the 1999-11-13 United States airing of <em>Who Wants to Be a Millionaire?</em>,
+and "In 1883, what industry led the movement to divide the U.S. into four time
+zones?" was a $32,000 question on the 2001-05-23 United States airing of
+the same show. At this rate, the million-dollar time-zone
+question should have been asked 2002-06-04.
+</li>
+<li>
+A private jet's mid-flight change of time zones distorts Alison Dubois'
+premonition in the "We Had a Dream" episode of <em>Medium</em>
+(originally aired 2007-02-28).
+</li>
+<li>
+A criminal's failure to account for the start of daylight saving is pivotal
+in "<a href="https://monk.fandom.com/wiki/Mr._Monk_and_the_Rapper">Mr. Monk
+and the Rapper</a>" (first aired 2007-07-20).
+</li>
+<li>
+In the <em>30 Rock</em> episode "Anna Howard Shaw Day"
+(first broadcast 2010-02-11),
+Jack Donaghy's date realizes that a Geneva-to-New-York business phone call
+received in the evening must be fake given the difference in local times.
+</li>
+<li>
+In the "Run by the Monkeys" episode of <em>Da Vinci's Inquest</em>
+(first broadcast 2002-11-17),
+a witness in a five-year-old fire case realizes they may not have set
+their clock back when daylight saving ended on the day of the fire,
+introducing the possibility of an hour when arson might have occurred.
+</li>
+<li>
+In "The Todd Couple" episode of <em>Outsourced</em> (first aired 2011-02-10),
+Manmeet sets up Valentine's Day teledates for 6:00 and 9:00pm;
+since one is with a New Yorker and the other with a San Franciscan,
+hilarity ensues.
+(Never mind that this should be 7:30am in Mumbai, yet for some reason the show
+proceeds as though it's also mid-evening there.)
+</li>
+<li>
+In the "14 Days to Go"/"T Minus..." episode of
+<em>You, Me and the Apocalypse</em>
+(first aired 2015-11-11 in the UK, 2016-03-10 in the US),
+the success of a mission to deal with a comet
+hinges on whether or not Russia observes daylight saving time.
+(In the US,
+the episode first aired in the week before the switch to <abbr>DST</abbr>.)
+</li>
+<li>
+"The Lost Hour", <em>Eerie, Indiana</em>, episode 10, NBC, 1991-12-01.
+Despite Indiana's then-lack of <abbr>DST</abbr>,
+Marshall changes his clock with unusual consequences.
+See "<a
+href="https://www.avclub.com/eerie-indiana-was-a-few-dimensions-ahead-of-its-time-1819833380"><em>Eerie,
+Indiana</em> was a few dimensions ahead of its time</a>".
+</li>
+<li>
+"Time Tunnel", <em>The Adventures of Pete &amp; Pete</em>, season 2, episode 5,
+Nickelodeon, 1994-10-23.
+The two Petes travel back in time an hour
+on the day that <abbr>DST</abbr> ends.
+</li>
+<li>
+"King-Size Homer", <em>The Simpsons</em>, episode 135, Fox, 1995-11-05.
+Homer, working from home, remarks "8:58, first
+time I've ever been early for work. Except for all those daylight
+savings days. Lousy farmers."
+</li>
+<li>
+<em>Last Week Tonight with John Oliver</em>, season 2, episode 5, 2015-03-08,
+asked, "<a href="https://www.youtube.com/watch?v=br0NW9ufUUw">Daylight Saving
+Time &ndash; How Is This Still A Thing?</a>"
+</li>
+<li>
+"Tracks", <em>The Good Wife</em>, season 7, episode 12,
+CBS, 2016-01-17.
+The applicability of a contract hinges on the
+time zone associated with a video timestamp.
+</li>
+<li>
+"Justice", <em>Veep</em>, season 6, episode 4, HBO, 2017-05-07.
+Jonah's inability to understand <abbr>DST</abbr> ends up impressing a wealthy
+backer who sets him up for a 2020 presidential run.
+</li>
+</ul>
+<h2>Books, plays, and magazines</h2>
+<ul>
+<li>
+Jules Verne, <em>Around the World in Eighty Days</em>
+(<em>Le tour du monde en quatre-vingts jours</em>), 1873.
+Wall-clock time plays a central role in the plot.
+European readers of the 1870s clearly held the U.S. press in
+deep contempt; the protagonists cross the U.S. without once
+reading a paper.
+Available versions include
+<a href="https://www.gutenberg.org/ebooks/103">an English
+translation</a>, and
+<a href="https://fourmilab.ch/etexts/www/tdm80j">the original French</a>
+"with illustrations from the original 1873 French-language edition".
+</li>
+<li>
+Nick Enright, <em>Daylight Saving</em>, 1989.
+A fast-paced comedy about love and loneliness as the clocks turn back.
+</li>
+<li>
+Umberto Eco,
+<a href="https://en.wikipedia.org/wiki/The_Island_of_the_Day_Before"><em>The
+Island of the Day Before</em></a>
+(<em>L'isola del giorno prima</em>), 1994.
+"...the story of a 17th century Italian nobleman trapped near an island
+on the International Date Line.  Time and time zones play an integral
+part in the novel." (Paul Eggert, 2006-04-22)
+</li>
+<li>
+John Dunning, <a
+href="https://www.simonandschuster.com/books/Two-OClock-Eastern-Wartime/John-Dunning/9781439171530"><em>Two
+O'Clock, Eastern Wartime</em></a>, 2001.
+Mystery, history, daylight saving time, and old-time radio.
+</li>
+<li>
+Surrealist artist Guy Billout's work "Date Line" appeared on page 103
+of the 1999-11 <em>Atlantic Monthly</em>.
+</li>
+<li>
+"Gloom, Gloom, Go Away" by Walter Kirn appeared on page 106 of <em>Time</em>
+magazine's 2002-11-11 issue; among other things, it proposed
+year-round <abbr>DST</abbr> as a way of lessening wintertime despair.
+</li>
+</ul>
+<h2>Music</h2>
+<p>
+Data on recordings of "Save That Time," Russ Long, Serrob Publishing, BMI:</p>
+<table>
+<tr><td>Artist</td><td>Karrin Allyson</td></tr>
+<tr><td>CD</td><td>I Didn't Know About You</td></tr>
+<tr><td>Copyright Date</td><td>1993</td></tr>
+<tr><td>Label</td><td>Concord Jazz, Inc.</td></tr>
+<tr><td>ID</td><td>CCD-4543</td></tr>
+<tr><td>Track Time</td><td>3:44</td></tr>
+<tr><td>Personnel</td><td>Karrin Allyson, vocal;
+Russ Long, piano;
+Gerald Spaits, bass;
+Todd Strait, drums</td></tr>
+<tr><td>Notes</td><td>CD notes "additional lyric by Karrin Allyson;
+arranged by Russ Long and Karrin Allyson"</td></tr>
+<tr><td>ADO Rating</td><td>1 star</td></tr>
+<tr><td><a href="https://www.allmusic.com/album/i-didnt-know-about-you-mw0000618657">AMG Rating</a></td><td>4 stars</td></tr>
+<tr><td>Penguin Rating</td><td>3.5 stars</td></tr>
+<tr><td>&nbsp;</td><td></td></tr>
+<tr><td>Artist</td><td>Kevin Mahogany</td></tr>
+<tr><td>CD</td><td>Double Rainbow</td></tr>
+<tr><td>Copyright Date</td><td>1993</td></tr>
+<tr><td>Label</td><td>Enja Records</td></tr>
+<tr><td>ID</td><td>ENJ-7097 2</td></tr>
+<tr><td>Track Time</td><td>6:27</td></tr>
+<tr><td>Personnel</td><td>Kevin Mahogany, vocal;
+Kenny Barron, piano;
+Ray Drummond, bass;
+Ralph Moore, tenor saxophone;
+Lewis Nash, drums</td></tr>
+<tr><td>ADO Rating</td><td>1.5 stars</td></tr>
+<tr><td><a href="https://www.allmusic.com/album/double-rainbow-mw0000620371">AMG Rating</a></td><td>3 stars</td></tr>
+<tr><td>Penguin Rating</td><td>3 stars</td></tr>
+<tr><td>&nbsp;</td><td></td></tr>
+<tr><td>Artist</td><td>Joe Williams</td></tr>
+<tr><td>CD</td><td>Here's to Life</td></tr>
+<tr><td>Copyright Date</td><td>1994</td></tr>
+<tr><td>Label</td><td>Telarc International Corporation</td></tr>
+<tr><td>ID</td><td>CD-83357</td></tr>
+<tr><td>Track Time</td><td>3:58</td></tr>
+<tr><td>Personnel</td><td>Joe Williams, vocal
+The Robert Farnon [39 piece] Orchestra</td></tr>
+<tr><td>Notes</td><td>This CD is also available as part of a 3-CD package from
+Telarc, "Triple Play" (CD-83461)</td></tr>
+<tr><td>ADO Rating</td><td>black dot</td></tr>
+<tr><td><a href="https://www.allmusic.com/album/heres-to-life-mw0000623648">AMG Rating</a></td><td>2 stars</td></tr>
+<tr><td>Penguin Rating</td><td>3 stars</td></tr>
+<tr><td>&nbsp;</td><td></td></tr>
+<tr><td>Artist</td><td>Charles Fambrough</td></tr>
+<tr><td>CD</td><td>Keeper of the Spirit</td></tr>
+<tr><td>Copyright Date</td><td>1995</td></tr>
+<tr><td>Label</td><td>AudioQuest Music</td></tr>
+<tr><td>ID</td><td>AQ-CD1033</td></tr>
+<tr><td>Track Time</td><td>7:07</td></tr>
+<tr><td>Personnel</td><td>Charles Fambrough, bass;
+Joel Levine, tenor recorder;
+Edward Simon, piano;
+Lenny White, drums;
+Marion Simon, percussion</td></tr>
+<tr><td>ADO Rating</td><td>2 stars</td></tr>
+<tr><td><a href="https://www.allmusic.com/album/keeper-of-the-spirit-mw0000176559">AMG Rating</a></td><td>unrated</td></tr>
+<tr><td>Penguin Rating</td><td>3 stars</td></tr>
+</table>
+<hr>
+<p>Also of note:</p>
+<table>
+<tr><td>Artist</td><td>Holly Cole Trio</td></tr>
+<tr><td>CD</td><td>Blame It On My Youth</td></tr>
+<tr><td>Copyright Date</td><td>1992</td></tr>
+<tr><td>Label</td><td>Manhattan</td></tr>
+<tr><td>ID</td><td>CDP 7 97349 2</td></tr>
+<tr><td>Total Time</td><td>37:45</td></tr>
+<tr><td>Personnel</td><td>Holly Cole, voice;
+Aaron Davis, piano;
+David Piltch, string bass</td></tr>
+<tr><td>Notes</td><td>Lyrical reference to "Eastern Standard Time" in
+Tom Waits' "Purple Avenue"</td></tr>
+<tr><td>ADO Rating</td><td>2.5 stars</td></tr>
+<tr><td><a href="https://www.allmusic.com/album/blame-it-on-my-youth-mw0000274303">AMG Rating</a></td><td>3 stars</td></tr>
+<tr><td>Penguin Rating</td><td>unrated</td></tr>
+<tr><td>&nbsp;</td><td></td></tr>
+<tr><td>Artist</td><td>Milt Hinton</td></tr>
+<tr><td>CD</td><td>Old Man Time</td></tr>
+<tr><td>Copyright Date</td><td>1990</td></tr>
+<tr><td>Label</td><td>Chiaroscuro</td></tr>
+<tr><td>ID</td><td>CR(D) 310</td></tr>
+<tr><td>Total Time</td><td>149:38 (two CDs)</td></tr>
+<tr><td>Personnel</td><td>Milt Hinton, bass;
+Doc Cheatham, Dizzy Gillespie, Clark Terry, trumpet;
+Al Grey, trombone;
+Eddie Barefield, Joe Camel (Flip Phillips), Buddy Tate,
+clarinet and saxophone;
+John Bunch, Red Richards, Norman Simmons, Derek Smith,
+Ralph Sutton, piano;
+Danny Barker, Al Casey, guitar;
+Gus Johnson, Gerryck King, Bob Rosengarden, Jackie Williams,
+drums;
+Lionel Hampton, vibraphone;
+Cab Calloway, Joe Williams, vocal;
+Buck Clayton, arrangements</td></tr>
+<tr><td>Notes</td><td>tunes include Old Man Time, Time After Time,
+Sometimes I'm Happy,
+A Hot Time in the Old Town Tonight,
+Four or Five Times, Now's the Time,
+Time on My Hands, This Time It's Us,
+and Good Time Charlie.
+<a href="http://www.chiaroscurojazz.com/album.php?C=310">Album info</a>
+is available.</td></tr>
+<tr><td>ADO Rating</td><td>3 stars</td></tr>
+<tr><td><a href="https://www.allmusic.com/album/old-man-time-mw0000269353">AMG Rating</a></td><td>4.5 stars</td></tr>
+<tr><td>Penguin Rating</td><td>3 stars</td></tr>
+<tr><td>&nbsp;</td><td></td></tr>
+<tr><td>Artist</td><td>Alan Broadbent</td></tr>
+<tr><td>CD</td><td>Pacific Standard Time</td></tr>
+<tr><td>Copyright Date</td><td>1995</td></tr>
+<tr><td>Label</td><td>Concord Jazz, Inc.</td></tr>
+<tr><td>ID</td><td>CCD-4664</td></tr>
+<tr><td>Total Time</td><td>62:42</td></tr>
+<tr><td>Personnel</td><td>Alan Broadbent, piano;
+Putter Smith, Bass;
+Frank Gibson, Jr., drums</td></tr>
+<tr><td>Notes</td><td>The CD cover features an analemma for equation-of-time fans</td></tr>
+<tr><td>ADO Rating</td><td>1 star</td></tr>
+<tr><td><a href="https://www.allmusic.com/album/pacific-standard-time-mw0000645433">AMG Rating</a></td><td>4 stars</td></tr>
+<tr><td>Penguin Rating</td><td>3.5 stars</td></tr>
+<tr><td>&nbsp;</td><td></td></tr>
+<tr><td>Artist</td><td>Anthony Braxton/Richard Teitelbaum</td></tr>
+<tr><td>CD</td><td>Silence/Time Zones</td></tr>
+<tr><td>Copyright Date</td><td>1996</td></tr>
+<tr><td>Label</td><td>Black Lion</td></tr>
+<tr><td>ID</td><td>BLCD 760221</td></tr>
+<tr><td>Total Time</td><td>72:58</td></tr>
+<tr><td>Personnel</td><td>Anthony Braxton, sopranino and alto saxophones,
+contrebasse clarinet, miscellaneous instruments;
+Leo Smith, trumpet and miscellaneous instruments;
+Leroy Jenkins, violin and miscellaneous instruments;
+Richard Teitelbaum, modular moog and micromoog synthesizer</td></tr>
+<tr><td>ADO Rating</td><td>black dot</td></tr>
+<tr><td><a href="https://www.allmusic.com/album/silence-time-zones-mw0000595735">AMG Rating</a></td><td>4 stars</td></tr>
+<tr><td>&nbsp;</td><td></td></tr>
+<tr><td>Artist</td><td>Charles Gayle</td></tr>
+<tr><td>CD</td><td>Time Zones</td></tr>
+<tr><td>Copyright Date</td><td>2006</td></tr>
+<tr><td>Label</td><td>Tompkins Square</td></tr>
+<tr><td>ID</td><td>TSQ2839</td></tr>
+<tr><td>Total Time</td><td>49:06</td></tr>
+<tr><td>Personnel</td><td>Charles Gayle, piano</td></tr>
+<tr><td>ADO Rating</td><td>1 star</td></tr>
+<tr><td><a href="https://www.allmusic.com/album/time-zones-mw0000349642">AMG Rating</a></td><td>4.5 stars</td></tr>
+<tr><td>&nbsp;</td><td></td></tr>
+<tr><td>Artist</td><td>The Get Up Kids</td></tr>
+<tr><td>CD</td><td>Eudora</td></tr>
+<tr><td>Copyright Date</td><td>2001</td></tr>
+<tr><td>Label</td><td>Vagrant</td></tr>
+<tr><td>ID</td><td>357</td></tr>
+<tr><td>Total Time</td><td>65:12</td></tr>
+<tr><td>Notes</td><td>Includes the song "Central Standard Time." Thanks to Colin Bowern for this information.</td></tr>
+<tr><td><a href="https://www.allmusic.com/album/eudora-mw0000592063">AMG Rating</a></td><td>2.5 stars</td></tr>
+<tr><td>&nbsp;</td><td></td></tr>
+
+<tr><td>Artist</td><td>Coldplay</td></tr>
+<tr><td>Song</td><td>Clocks</td></tr>
+<tr><td>Copyright Date</td><td>2003</td></tr>
+<tr><td>Label</td><td>Capitol Records</td></tr>
+<tr><td>ID</td><td>52608</td></tr>
+<tr><td>Total Time</td><td>4:13</td></tr>
+<tr><td>Notes</td><td>Won the 2004 Record of the Year honor at the
+Grammy Awards. Co-written and performed by Chris Martin,
+great-great-grandson of <abbr>DST</abbr> inventor William Willett.
+The song's first line is "Lights go out and I can't be saved".</td></tr>
+<tr><td>&nbsp;</td><td></td></tr>
+
+<tr><td>Artist</td><td>Jaime Guevara</td></tr>
+<tr><td>Song</td><td><a
+href="https://www.youtube.com/watch?v=ZfN4Fe_A50U">Qu&eacute;
+hora es</a></td></tr>
+<tr><td>Date</td><td>1993</td></tr>
+<tr><td>Total Time</td><td>3:04</td></tr>
+<tr><td>Notes</td><td>The song protested "Sixto Hour" in Ecuador
+(1992&ndash;3). Its lyrics include "Amanec&iacute;a en mitad de la noche, los
+guaguas iban a clase sin sol" ("It was dawning in the middle of the
+night, the buses went to class without sun").
+<tr><td>&nbsp;</td><td></td></tr>
+
+<tr><td>Artist</td><td>Irving Kahal and Harry Richman</td></tr>
+<tr><td>Song</td><td>There Ought to be a Moonlight Saving Time</td></tr>
+<tr><td>Copyright Date</td><td>1931</td>
+<tr><td>Notes</td><td>This musical standard was a No. 1 hit for Guy Lombardo
+in 1931, and was also performed by Maurice Chevalier, Blossom Dearie
+and many others. The phrase "Moonlight saving time" also appears in
+the 1995 country song "Not Enough Hours in the Night" written by Aaron
+Barker, Kim Williams and Rob Harbin and performed by Doug
+Supernaw.</td></tr>
+<tr><td>&nbsp;</td><td></td></tr>
+
+<tr><td>Artist</td><td>The Microscopic Septet</td></tr>
+<tr><td>CD</td><td>Lobster Leaps In</td></tr>
+<tr><td>Copyright Date</td><td>2008</td></tr>
+<tr><td>Label</td><td>Cuneiform</td></tr>
+<tr><td>ID</td><td>272</td></tr>
+<tr><td>Total Time</td><td>73:05</td></tr>
+<tr><td>Notes</td><td>Includes the song "Twilight Time Zone."</td></tr>
+<tr><td><a href="https://www.allmusic.com/album/lobster-leaps-in-mw0000794929">AMG Rating</a></td><td>3.5 stars</td></tr>
+<tr><td>ADO Rating</td><td>2 stars</td></tr>
+
+<tr><td>&nbsp;</td><td></td></tr>
+
+<tr><td>Artist</td><td>Bob Dylan</td></tr>
+<tr><td>CD</td><td>The Times They Are a-Changin'</td></tr>
+<tr><td>Copyright Date</td><td>1964</td></tr>
+<tr><td>Label</td><td>Columbia</td></tr>
+<tr><td>ID</td><td>CK-8905</td></tr>
+<tr><td>Total Time</td><td>45:36</td></tr>
+<tr><td><a href="https://www.allmusic.com/album/the-times-they-a-changin-mw0000202344">AMG Rating</a></td><td>4.5 stars</td></tr>
+<tr><td>ADO Rating</td><td>1.5 stars</td></tr>
+<tr><td>Notes<td>The title song is also available on "Bob Dylan's Greatest Hits" and "The Essential Bob Dylan."</td></tr>
+<tr><td>&nbsp;</td><td></td></tr>
+
+<tr><td>Artist</td><td>Luciana Souza</td></tr>
+<tr><td>CD</td><td>Tide</td></tr>
+<tr><td>Copyright Date</td><td>2009</td></tr>
+<tr><td>Label</td><td>Universal Jazz France</td></tr>
+<tr><td>ID</td><td>B0012688-02</td></tr>
+<tr><td>Total Time</td><td>42:31</td></tr>
+<tr><td><a href="https://www.allmusic.com/album/tide-mw0000815692">AMG Rating</a></td><td>3.5 stars</td></tr>
+<tr><td>ADO Rating</td><td>2.5 stars</td></tr>
+<tr><td>Notes<td>Includes the song "Fire and Wood" with the lyric
+"The clocks were turned back you remember/Think it's still November."
+</td></tr>
+<tr><td>&nbsp;</td><td></td></tr>
+<tr><td>Artist</td><td>Ken Nordine</td></tr>
+<tr><td>CD</td><td>You're Getting Better: The Word Jazz Dot Masters</td></tr>
+<tr><td>Copyright Date</td><td>2005</td></tr>
+<tr><td>Label</td><td>Geffen</td></tr>
+<tr><td>ID</td><td>B0005171-02</td></tr>
+<tr><td>Total Time</td><td>156:22</td></tr>
+<tr><td>ADO Rating</td><td>1 star</td></tr>
+<tr><td><a href="https://www.allmusic.com/album/youre-getting-better-the-word-jazz-dot-masters-mw0000736197">AMG Rating</a></td><td>4.5 stars</td></tr>
+<tr><td>Notes</td><td>Includes the piece "What Time Is It"
+("He knew what time it was everywhere...that counted").</td></tr>
+<tr><td>&nbsp;</td><td></td></tr>
+<tr><td>Artist</td><td>Chicago</td></tr>
+<tr><td>CD</td><td>Chicago Transit Authority</td></tr>
+<tr><td>Copyright Date</td><td>1969</td></tr>
+<tr><td>Label</td><td>Columbia</td></tr>
+<tr><td>ID</td><td>64409</td></tr>
+<tr><td>Total Time</td><td>1:16:20</td></tr>
+<tr><td><a href="https://www.allmusic.com/album/chicago-transit-authority-mw0000189364">AMG Rating</a></td><td>4 stars</td></tr>
+<tr><td>Notes</td><td>Includes the song "Does Anybody Really Know What Time It Is?"</td></tr>
+</table>
+<h2>Comics</h2>
+<ul>
+<li>
+The webcomic <em>xkcd</em> has the strip
+"<a href="https://xkcd.com/673/">The Sun</a>" (2009-12-09) and the panels
+"<a href="https://xkcd.com/1017/">Backward in Time</a>" (2012-02-14),
+"<a href="https://xkcd.com/1061/">EST</a>" (2012-05-28),
+"<a href="https://xkcd.com/1179/">ISO 8601</a>" (2013-02-27),
+"<a href="https://xkcd.com/1335/">Now</a>" (2014-02-26),
+"<a href="https://xkcd.com/1655/">Doomsday Clock</a>" (2016-03-14),
+"<a href="https://xkcd.com/1799/">Bad Map Projection: Time Zones</a>"
+(2017-02-15),
+"<a href="https://xkcd.com/1883/">Supervillain Plan</a>" (2017-08-30),
+"<a href="https://xkcd.com/2050/">6/6 Time</a>" (2018-09-24),
+and "<a href="https://xkcd.com/2266/">Leap Smearing</a>" (2020-02-10).
+The related book <em>What If?</em> has an entry
+"<a href="https://what-if.xkcd.com/26/">Leap Seconds</a>" (2012-12-31).
+</li>
+<li>
+Pig kills time in <a
+href="https://www.gocomics.com/pearlsbeforeswine/2016/11/06"><em>Pearls
+Before Swine</em> (2016-11-06)</a>.
+</li>
+<li>
+Stonehenge is abandoned in <a
+href="https://www.gocomics.com/nonsequitur/2017/03/12"><em>Non Sequitur</em>
+(2017-03-12)</a>.
+<li>
+The boss freaks out in <a
+href="https://dilbert.com/strip/1998-03-14"><em>Dilbert</em> (1998-03-14)</a>.
+</li>
+<li>
+Peppermint Patty: "What if the world comes to an end tonight, Marcie?"
+<br>
+Marcie: "I promise there'll be a tomorrow, sir ... in fact,
+it's already tomorrow in Australia!"
+<br>
+(Charles M. Schulz, <a href="https://www.gocomics.com/peanuts/1980/06/13"><em>Peanuts</em>, 1980-06-13</a>)
+</li>
+</ul>
+<h2>Jokes</h2>
+<ul>
+<li>
+The idea behind daylight saving time was first proposed as a joke by
+Benjamin Franklin. To enforce it, he suggested, "Every
+morning, as soon as the sun rises, let all the bells in every church
+be set ringing; and if that is not sufficient, let cannon be fired in
+every street, to wake the sluggards effectually, and make them open
+their eyes to see their true interest. All the difficulty will be in
+the first two or three days: after which the reformation will be as
+natural and easy as the present irregularity; for, <em>ce n'est que le
+premier pas qui co&ucirc;te</em>."
+<a href="http://www.webexhibits.org/daylightsaving/franklin3.html">Franklin's
+joke</a> was first published on 1784-04-26 by the
+<em>Journal de Paris</em> as <a
+href="https://en.wikipedia.org/wiki/File:Franklin-Benjamin-Journal-de-Paris-1784.jpg">an
+anonymous letter translated into French</a>.
+</li>
+<li>
+"We've been using the five-cent nickel in this country since 1492.
+Now that's pretty near 100 years, daylight saving."
+(Groucho Marx as Captain Spaulding in <em>Animal Crackers</em>, 1930,
+as noted by Will Fitzgerald)
+</li>
+<li>
+BRADY. ...[Bishop Usher] determined that the Lord began the Creation
+on the 23rd of October in the Year 4,004 B.C. at &ndash; uh, 9 A.M.!
+<br>
+DRUMMOND. That Eastern Standard Time? (<em>Laughter.</em>) Or Rocky Mountain
+Time? (<em>More laughter.</em>) It wasn't daylight-saving time, was it? Because
+the Lord didn't make the sun until the fourth day!
+<br>
+(From the play <em>Inherit the Wind</em> by Jerome Lawrence and Robert E. Lee,
+filmed in 1960 with Spencer Tracy as Drummond and Fredric March as
+Brady, and several other times. Thanks to Mark Brader.)
+</li>
+<li>
+"Good news."
+"What did they do? Extend Daylight Saving Time year round?"
+(Professional tanner George Hamilton, in dialog from a
+May, 1999 episode of the syndicated television series <em>Baywatch</em>)
+</li>
+<li>
+"A fundamental belief held by Americans is that if you are on land, you
+cannot be killed by a fish...So most Americans remain on land, believing
+they're safe. Unfortunately, this belief &ndash; like so many myths, such as that
+there's a reason for 'Daylight Saving Time' &ndash; is false."
+(Dave Barry column, 2000-07-02)
+</li>
+<li>
+"I once had sex for an hour and five minutes, but that was on the day
+when you turn the clocks ahead."
+(Garry Shandling, 52nd Annual Emmys, 2000-09-10)
+</li>
+<li>
+"Would it impress you if I told you I invented Daylight Savings Time?"
+("Sahjhan" to "Lilah" in dialog from the "Loyalty" episode of <em>Angel</em>,
+originally aired 2002-02-25)
+</li>
+<li>
+"I thought you said Tulsa was a three-hour flight."
+"Well, you're forgetting about the time difference."
+("Joey" and "Chandler" in dialog from the episode of <em>Friends</em>
+entitled "The One With Rachel's Phone Number," originally aired 2002-12-05)
+</li>
+<li>
+"Is that a pertinent fact,
+or are you just trying to dazzle me with your command of time zones?"
+(Kelsey Grammer as "Frasier Crane" to "Roz" from the episode of <em>Frasier</em>
+entitled "The Kid," originally aired 1997-11-04)
+</li>
+<li>
+"I put myself and my staff through this crazy, huge ordeal, all because
+I refused to go on at midnight, okay?  And so I work, you know, and
+then I get this job at eleven, supposed to be a big deal.  Then
+yesterday daylight [saving] time ended. Right now it's basically
+midnight." (Conan O'Brien on the 2010-11-08 premiere of <em>Conan</em>.)
+</li>
+<li>
+"The best method, I told folks, was to hang a large clock high on a
+barn wall where all the cows could see it. If you have Holsteins, you
+will need to use an analog clock." (Jerry Nelson, <a
+href="http://www.agriculture.com/family/farm-humor/how-to-adjust-dairy-cows-to-daylight-savings-time">How
+to adjust dairy cows to daylight saving time</a>", <em>Successful Farming</em>,
+2017-10-09.)
+</li>
+<li>
+"And now, driving to California, I find that I must enter a password
+in order to change the time zone on my laptop clock. Evidently,
+someone is out to mess up my schedule and my clock must be secured."
+(Garrison Keillor,
+"<a href="http://www.garrisonkeillor.com/weve-never-been-here-before/">We've
+never been here before</a>", 2017-08-22)
+</li>
+<li>
+"Well, in my time zone that's all the time I have,
+but maybe in your time zone I haven't finished yet. So stay tuned!"
+(Goldie Hawn, <em>Rowan &amp; Martin's Laugh-In</em> No. 65, 1970-03-09)
+</li>
+</ul>
+<h2>See also</h2>
+<ul>
+<li><a href="tz-link.html">Time Zone and Daylight Saving
+Time Data</a></li>
+</ul>
+<hr>
+<address>
+This web page is in the public domain, so clarified as of
+2009-05-17 by Arthur David Olson.
+<br>
+Please send corrections to this web page to the
+<a href="mailto:tz@iana.org">time zone mailing list</a>.
+</address>
+</body>
+</html>
diff --git a/contrib/tzcode/tz-how-to.html b/contrib/tzcode/tz-how-to.html
new file mode 100644
index 000000000000..e1e28f2e257d
--- /dev/null
+++ b/contrib/tzcode/tz-how-to.html
@@ -0,0 +1,719 @@
+<!DOCTYPE html>
+<html lang="en">
+<head>
+<title>How to Read the tz Database</title>
+<meta charset="UTF-8">
+<style>
+pre {margin-left: 2em; white-space: pre-wrap;}
+pre.td {margin-left: 0;}
+td {text-align: center;}
+table {border: 1px outset;}
+th, td {border: 1px inset;}
+table.rule {border: none; margin: auto;}
+td.footnote {text-align: left;}
+</style>
+</head>
+<body>
+<h2>How to Read the <a href="https://en.wikipedia.org/wiki/Tz_database">tz
+Database</a> Source Files</h2>
+<h3>by Bill Seymour</h3>
+<p>This guide uses the <code>America/Chicago</code> and
+<code>Pacific/Honolulu</code> zones as examples of how to infer
+times of day from the <a href="tz-link.html">tz database</a>
+source files. It might be helpful, but not absolutely necessary,
+for the reader to have already downloaded the
+latest release of the database and become familiar with the basic layout
+of the data files. The format is explained in the &ldquo;man
+page&rdquo; for the zic compiler, <code>zic.8.txt</code>, in
+the <code>code</code> subdirectory.
+Although this guide covers many of the common cases, it is not a
+complete summary of what zic accepts; the man page is the
+authoritative reference.</p>
+
+<p>We&rsquo;ll begin by talking about the rules for changing between standard
+and daylight saving time since we&rsquo;ll need that information when we talk
+about the zones.</p>
+
+<p>First, let&rsquo;s consider the special daylight saving time rules
+for Chicago (from the <code>northamerica</code> file in
+the <code>data</code> subdirectory):</p>
+
+<table>
+<tr>
+  <th colspan="6">From the Source File</th>
+</tr>
+<tr>
+  <td colspan="6">
+    <table class="rule">
+      <tr><td style="border:none;text-align:left">
+<pre class="td">
+#Rule NAME    FROM TO    -   IN  ON      AT   SAVE LETTER
+Rule  Chicago 1920 only  -   Jun 13      2:00 1:00 D
+Rule  Chicago 1920 1921  -   Oct lastSun 2:00 0    S
+Rule  Chicago 1921 only  -   Mar lastSun 2:00 1:00 D
+Rule  Chicago 1922 1966  -   Apr lastSun 2:00 1:00 D
+Rule  Chicago 1922 1954  -   Sep lastSun 2:00 0    S
+Rule  Chicago 1955 1966  -   Oct lastSun 2:00 0    S
+</pre>
+  </td></tr></table></td>
+</tr>
+<tr>
+  <th colspan="6">Reformatted a Bit</th>
+</tr>
+<tr>
+  <th>From</th>
+  <th>To</th>
+  <th colspan="2">On</th>
+  <th>At</th>
+  <th>Action</th>
+</tr>
+<tr>
+  <td colspan="2">1920 only</td>
+  <td colspan="2">June 13<small><sup>th</sup></small></td>
+  <td rowspan="6">02:00 local</td>
+  <td>go to daylight saving time</td>
+</tr>
+<tr>
+  <td>1920</td>
+  <td>1921</td>
+  <td rowspan="5">last Sunday</td>
+  <td>in October</td>
+  <td>return to standard time</td>
+</tr>
+<tr>
+  <td colspan="2">1921 only</td>
+  <td>in March</td>
+  <td rowspan="2">go to daylight saving time</td>
+</tr>
+<tr>
+  <td rowspan="2">1922</td>
+  <td>1966</td>
+  <td>in April</td>
+</tr>
+<tr>
+  <td>1954</td>
+  <td>in September</td>
+  <td rowspan="2">return to standard time</td>
+</tr>
+<tr>
+  <td>1955</td>
+  <td>1966</td>
+  <td>in October</td>
+</tr>
+</table>
+
+<p>The <code>FROM</code> and <code>TO</code> columns, respectively, specify the
+first and last calendar years defining a contiguous range over which a specific
+Rule line is to apply.  The keyword <code>only</code> can be used in the
+<code>TO</code> field to repeat the value of the <code>FROM</code> field in the
+event that a rule should only apply to a single year.  Often, the keyword
+<code>max</code> is used to extend a rule&rsquo;s application into the
+indefinite future; it is a platform-agnostic stand-in for the largest
+representable year.
+
+<p>The next column, <code>-</code>, is reserved; for compatibility with earlier
+releases, it always contains a hyphen, which acts as a kind of null value.
+Prior to the 2020b release, it was called the <code>TYPE</code> field, though
+it had not been used in the main data since the 2000e release.
+An obsolescent supplementary file used the
+field as a proof-of-concept to allow <code>zic</code> to apply a given Rule
+line only to certain &ldquo;types&rdquo; of years within the specified range as
+dictated by the output of a separate script, such as: only years which would
+have a US presidential election, or only years which wouldn&rsquo;t.
+
+<p>The <code>SAVE</code> column contains the local (wall clock) offset from
+local standard time.
+This is usually either zero for standard time or one hour for daylight
+saving time; but there&rsquo;s no reason, in principle, why it can&rsquo;t
+take on other values.
+
+<p>The <code>LETTER</code> (sometimes called <code>LETTER/S</code>)
+column can contain a variable
+part of the usual abbreviation of the time zone&rsquo;s name, or it can just
+be a hyphen if there&rsquo;s no variable part. For example, the abbreviation
+used in the central time zone will be either &ldquo;CST&rdquo; or
+&ldquo;CDT&rdquo;. The variable part is &lsquo;S&rsquo; or &lsquo;D&rsquo;;
+and, sure enough, that&rsquo;s just what we find in
+the <code>LETTER</code> column
+in the <code>Chicago</code> rules. More about this when we talk about
+&ldquo;Zone&rdquo; lines.
+
+<p>One important thing to notice is that &ldquo;Rule&rdquo; lines
+want at once to be both <i>transitions</i> and <i>steady states</i>:
+<ul>
+<li>On the one hand, they represent transitions between standard and
+daylight saving time; and any number of Rule lines can be in effect
+during a given period (which will always be a non-empty set of
+contiguous calendar years).</li>
+<li>On the other hand, the <code>SAVE</code> and <code>LETTER</code>
+columns contain state that exists between transitions. More about this
+when we talk about the US rules.</li>
+</ul>
+
+<p>In the example above, the transition to daylight saving time
+happened on the 13<small><sup>th</sup></small> of June in 1920, and on
+the last Sunday in March in 1921; but the return to standard time
+happened on the last Sunday in October in both of those
+years. Similarly, the rule for changing to daylight saving time was
+the same from 1922 to 1966; but the rule for returning to standard
+time changed in 1955. Got it?</p>
+
+<p>OK, now for the somewhat more interesting &ldquo;US&rdquo; rules:</p>
+
+<table>
+<tr>
+  <th colspan="6">From the Source File</th>
+</tr>
+<tr>
+  <td colspan="6">
+    <table class="rule">
+      <tr><td style="border:none;text-align:left">
+<pre class="td">
+#Rule NAME FROM TO    -   IN  ON        AT   SAVE LETTER/S
+Rule  US   1918 1919  -   Mar lastSun  2:00  1:00 D
+Rule  US   1918 1919  -   Oct lastSun  2:00  0    S
+Rule  US   1942 only  -   Feb 9        2:00  1:00 W # War
+Rule  US   1945 only  -   Aug 14      23:00u 1:00 P # Peace
+Rule  US   1945 only  -   Sep 30       2:00  0    S
+Rule  US   1967 2006  -   Oct lastSun  2:00  0    S
+Rule  US   1967 1973  -   Apr lastSun  2:00  1:00 D
+Rule  US   1974 only  -   Jan 6        2:00  1:00 D
+Rule  US   1975 only  -   Feb 23       2:00  1:00 D
+Rule  US   1976 1986  -   Apr lastSun  2:00  1:00 D
+Rule  US   1987 2006  -   Apr Sun&gt;=1   2:00  1:00 D
+Rule  US   2007 max   -   Mar Sun&gt;=8   2:00  1:00 D
+Rule  US   2007 max   -   Nov Sun&gt;=1   2:00  0    S
+</pre>
+  </td></tr></table></td>
+</tr>
+<tr>
+  <th colspan="6">Reformatted a Bit</th>
+</tr>
+<tr>
+  <th>From</th>
+  <th>To</th>
+  <th colspan="2">On</th>
+  <th>At</th>
+  <th>Action</th>
+</tr>
+<tr>
+  <td rowspan="2">1918</td>
+  <td rowspan="2">1919</td>
+  <td rowspan="2">last Sunday</td>
+  <td>in March</td>
+  <td rowspan="3">02:00 local</td>
+  <td>go to daylight saving time</td>
+</tr>
+<tr>
+  <td>in October</td>
+  <td>return to standard time</td>
+</tr>
+<tr>
+  <td colspan="2">1942 only</td>
+  <td colspan="2">February 9<small><sup>th</sup></small></td>
+  <td>go to &ldquo;war time&rdquo;</td>
+</tr>
+<tr>
+  <td colspan="2" rowspan="2">1945 only</td>
+  <td colspan="2">August 14<small><sup>th</sup></small></td>
+  <td>23:00 <a href="https://en.wikipedia.org/wiki/Universal_Time">UT</a></td>
+  <td>
+    rename &ldquo;war time&rdquo; to &ldquo;peace<br>time;&rdquo;
+    clocks don&rsquo;t change
+  </td>
+</tr>
+<tr>
+  <td colspan="2">September 30<small><sup>th</sup></small></td>
+  <td rowspan="9">02:00 local</td>
+  <td rowspan="2">return to standard time</td>
+</tr>
+<tr>
+  <td rowspan="2">1967</td>
+  <td>2006</td>
+  <td rowspan="2">last Sunday</td>
+  <td>in October</td>
+</tr>
+<tr>
+  <td>1973</td>
+  <td>in April</td>
+  <td rowspan="6">go to daylight saving time</td>
+</tr>
+<tr>
+  <td colspan="2">1974 only</td>
+  <td colspan="2">January 6<small><sup>th</sup></small></td>
+</tr>
+<tr>
+  <td colspan="2">1975 only</td>
+  <td colspan="2">February 23<small><sup>rd</sup></small></td>
+</tr>
+<tr>
+  <td>1976</td>
+  <td>1986</td>
+  <td>last Sunday</td>
+  <td rowspan="2">in April</td>
+</tr>
+<tr>
+  <td>1987</td>
+  <td>2006</td>
+  <td>first Sunday</td>
+</tr>
+<tr>
+  <td rowspan="2">2007</td>
+  <td rowspan="2">present</td>
+  <td colspan="2">second Sunday in March</td>
+</tr>
+<tr>
+  <td colspan="2">first Sunday in November</td>
+  <td>return to standard time</td>
+</tr>
+</table>
+
+<p>There are two interesting things to note here.</p>
+
+<p>First, the time that something happens (in the <code>AT</code>
+column) is not necessarily the local (wall clock) time. The time can be
+suffixed with &lsquo;s&rsquo; (for &ldquo;standard&rdquo;) to mean
+local standard time, different from local (wall clock) time when observing
+daylight saving time; or it can be suffixed with &lsquo;g&rsquo;,
+&lsquo;u&rsquo;, or &lsquo;z&rsquo;, all three of which mean the
+standard time at the
+<a href="https://en.wikipedia.org/wiki/Prime_Meridian">prime meridian</a>.
+&lsquo;g&rsquo; stands for &ldquo;<a
+href="https://en.wikipedia.org/wiki/Greenwich_Mean_Time">GMT</a>&rdquo;;
+&lsquo;u&rsquo; stands for &ldquo;<a
+href="https://en.wikipedia.org/wiki/Universal_Time">UT</a>&rdquo; or &ldquo;<a
+href="https://en.wikipedia.org/wiki/Coordinated_Universal_Time">UTC</a>&rdquo;
+(whichever was official at the time); &lsquo;z&rsquo; stands for the
+<a href="https://en.wikipedia.org/wiki/Nautical_time">nautical time zone</a>
+Z (a.k.a. &ldquo;Zulu&rdquo; which, in turn, stands for &lsquo;Z&rsquo;).
+The time can also be suffixed with &lsquo;w&rsquo; meaning local (wall
+clock) time; but it usually isn&rsquo;t because that&rsquo;s the
+default.</p>
+
+<p>Second, the day in the <code>ON</code> column, in addition to
+&ldquo;<code>lastSun</code>&rdquo; or a particular day of the month,
+can have the form, &ldquo;<code>Sun&gt;=</code><i>x</i>&rdquo; or
+&ldquo;<code>Sun&lt;=</code><i>x</i>,&rdquo; where <i>x</i> is a day
+of the month. For example, &ldquo;<code>Sun&gt;=8</code>&rdquo; means
+&ldquo;the first Sunday on or after the eighth of the month,&rdquo; in
+other words, the second Sunday of the month. Furthermore, although
+there are no examples above, the weekday needn&rsquo;t be
+&ldquo;<code>Sun</code>&rdquo; in either form, but can be the usual
+three-character English abbreviation for any day of the week.</p>
+
+<p>And the US rules give us more examples of a couple of things
+already mentioned:</p>
+
+<ul>
+<li>The rules for changing to and from daylight saving time are
+actually <i>different sets</i> of rules; and the two sets can change
+independently. Consider, for example, that the rule for the return to
+standard time stayed the same from 1967 to 2006; but the rule for the
+transition to daylight saving time changed several times in the same
+period.  There can also be periods, 1946 to 1966 for example, when no
+rule from this group is in effect, and so either no transition
+happened in those years, or some other rule is in effect (perhaps a
+state or other more local rule).</li>
+
+<li>The <code>SAVE</code> and <code>LETTER</code> columns
+contain <i>steady state</i>, not transitions. Consider, for example,
+the transition from &ldquo;war time&rdquo; to &ldquo;peace time&rdquo;
+that happened on August 14, 1945. The &ldquo;1:00&rdquo; in
+the <code>SAVE</code> column is <i>not</i> an instruction to advance
+the clock an hour. It means that clocks should <i>be</i> one hour
+ahead of standard time, which they already are because of the previous
+rule, so there should be no change.</li>
+
+</ul>
+
+<p>OK, now let&rsquo;s look at a Zone record:</p>
+
+<table>
+<tr>
+  <th colspan="5">From the Source File</th>
+</tr>
+<tr>
+  <td colspan="5">
+    <table class="rule">
+      <tr><td style="border:none;text-align:left">
+<pre class="td">
+#Zone       NAME      STDOFF   RULES FORMAT [UNTIL]
+Zone  America/Chicago -5:50:36 -       LMT  1883 Nov 18 12:09:24
+                      -6:00    US      C%sT 1920
+                      -6:00    Chicago C%sT 1936 Mar  1  2:00
+                      -5:00    -       EST  1936 Nov 15  2:00
+                      -6:00    Chicago C%sT 1942
+                      -6:00    US      C%sT 1946
+                      -6:00    Chicago C%sT 1967
+                      -6:00    US      C%sT
+</pre>
+  </td></tr></table></td>
+</tr>
+<tr>
+  <th colspan="5">Columns Renamed</th>
+</tr>
+<tr>
+  <th rowspan="2">Standard Offset<br>
+    from <a href="https://en.wikipedia.org/wiki/Prime_Meridian">Prime
+    Meridian</a></th>
+  <th rowspan="2">Daylight<br>Saving Time</th>
+  <th rowspan="2">Abbreviation(s)</th>
+  <th colspan="2">Ending at Local Time</th>
+</tr>
+<tr>
+  <th>Date</th>
+  <th>Time</th>
+</tr>
+<tr>
+  <td>&minus;5:50:36</td>
+  <td>not observed</td>
+  <td>LMT</td>
+  <td>1883-11-18</td>
+  <td>12:09:24</td>
+</tr>
+<tr>
+  <td rowspan="2">&minus;6:00:00</td>
+  <td>US rules</td>
+  <td rowspan="2">CST or CDT</td>
+  <td>1920-01-01</td>
+  <td>00:00:00</td>
+</tr>
+<tr>
+  <td>Chicago rules</td>
+  <td>1936-03-01</td>
+  <td rowspan="2">02:00:00</td>
+</tr>
+<tr>
+  <td>&minus;5:00:00</td>
+  <td>not observed</td>
+  <td>EST</td>
+  <td>1936-11-15</td>
+</tr>
+<tr>
+  <td rowspan="4">&minus;6:00:00</td>
+  <td>Chicago rules</td>
+  <td>CST or CDT</td>
+  <td>1942-01-01</td>
+  <td rowspan="3">00:00:00</td>
+</tr>
+<tr>
+  <td>US rules</td>
+  <td>CST, CWT or CPT</td>
+  <td>1946-01-01</td>
+</tr>
+<tr>
+  <td>Chicago rules</td>
+  <td rowspan="2">CST or CDT</td>
+  <td>1967-01-01</td>
+</tr>
+<tr>
+  <td>US rules</td>
+  <td colspan="2">&mdash;</td>
+</tr>
+</table>
+
+<p>There are a couple of interesting differences between Zones and Rules.</p>
+
+<p>First, and somewhat trivially, whereas Rules are considered to
+contain one or more records, a Zone is considered to be a single
+record with zero or more <i>continuation lines</i>. Thus, the keyword,
+&ldquo;<code>Zone</code>,&rdquo; and the zone name are not
+repeated. The last line is the one without anything in
+the <code>[UNTIL]</code> column.</p>
+
+<p>Second, and more fundamentally, each line of a Zone represents a
+steady state, not a transition between states. The state exists from
+the date and time in the previous line&rsquo;s <code>[UNTIL]</code>
+column up to the date and time in the current
+line&rsquo;s <code>[UNTIL]</code> column. In other words, the date and
+time in the <code>[UNTIL]</code> column is the instant that separates
+this state from the next. Where that would be ambiguous because
+we&rsquo;re setting our clocks back, the <code>[UNTIL]</code> column
+specifies the first occurrence of the instant. The state specified by
+the last line, the one without anything in the <code>[UNTIL]</code>
+column, continues to the present.</p>
+
+<p>The first line typically specifies the mean solar time observed
+before the introduction of standard time. Since there&rsquo;s no line before
+that, it has no beginning. <code>8-) </code> For some places near the <a
+href="https://en.wikipedia.org/wiki/International_Date_Line">International
+Date Line</a>, the first <i>two</i> lines will show solar times
+differing by 24 hours; this corresponds to a movement of the Date
+Line.  For example:</p>
+
+<pre>
+#Zone NAME          STDOFF   RULES FORMAT [UNTIL]
+Zone America/Juneau 15:02:19 -     LMT    1867 Oct 18
+                    -8:57:41 -     LMT    ...
+</pre>
+
+<p>When Alaska was purchased from Russia in 1867, the Date Line moved
+from the Alaska/Canada border to the Bering Strait; and the time in
+Alaska was then 24 hours earlier than it had
+been. <code>&lt;aside&gt;</code>(6 October in the Julian calendar,
+which Russia was still using then for religious reasons, was followed
+by <i>a second instance of the same day with a different name</i>, 18
+October in the Gregorian calendar. Isn&rsquo;t civil time
+wonderful? <code>8-)</code>)<code>&lt;/aside&gt;</code></p>
+
+<p>The abbreviation, &ldquo;LMT&rdquo; stands for &ldquo;local mean
+time&rdquo;, which is an invention of
+the <a href="https://en.wikipedia.org/wiki/Tz_database">tz
+database</a> and was probably never actually used during the
+period. Furthermore, the value is almost certainly wrong except in the
+archetypal place after which the zone is named. (The tz database
+usually doesn&rsquo;t provide a separate Zone record for places where
+nothing significant happened after 1970.)</p>
+
+<p>The <code>RULES</code> column tells us whether daylight saving time is being observed:
+<ul>
+<li>A hyphen, a kind of null value, means that we have not set our
+clocks ahead of standard time.</li>
+
+<li>An amount of time (usually but not necessarily &ldquo;1:00&rdquo;
+meaning one hour) means that we have set our clocks ahead by that
+amount.</li>
+
+<li>Some alphabetic string means that we <i>might have</i> set our
+clocks ahead; and we need to check the rule the name of which is the
+given alphabetic string.</li>
+</ul>
+
+<p>An example of a specific amount of time is:</p>
+<pre>
+#Zone NAME            STDOFF RULES FORMAT [UNTIL]
+Zone Pacific/Honolulu ...                 1933 Apr 30  2:00
+                      -10:30 1:00  HDT    1933 May 21 12:00
+                      ...
+</pre>
+
+<p>Hawaii tried daylight saving time for three weeks in 1933 and
+decided they didn&rsquo;t like it. <code>8-) </code>Note that
+the <code>STDOFF</code> column always contains the standard time
+offset, so the local (wall clock) time during this period was GMT &minus;
+10:30 + 1:00 = GMT &minus; 9:30.</p>
+
+<p>The <code>FORMAT</code> column specifies the usual abbreviation of
+the time zone name. It should have one of four forms:</p>
+<ul>
+
+<li>a time zone abbreviation that is a string of three or more
+characters that are either ASCII alphanumerics,
+&ldquo;<code>+</code>&rdquo;, or &ldquo;<code>-</code>&rdquo;</li>
+
+<li>the string &ldquo;%z&rdquo;, in which case the
+&ldquo;<code>%z</code>&rdquo; will be replaced by a numeric time zone
+abbreviation</li>
+
+<li>a pair of time zone abbreviations separated by a slash
+(&lsquo;<code>/</code>&rsquo;), in which case the first string is the
+abbreviation for the standard time name and the second string is the
+abbreviation for the daylight saving time name</li>
+
+<li>a string containing &ldquo;<code>%s</code>&rdquo;, in which case
+the &ldquo;<code>%s</code>&rdquo; will be replaced by the text in the
+appropriate Rule&rsquo;s <code>LETTER</code> column, and the resulting
+string should be a time zone abbreviation</li>
+</ul>
+
+<p>The last two make sense only if there&rsquo;s a named rule in effect.</p>
+
+<p>An example of a slash is:</p>
+<pre>
+#Zone NAME          STDOFF RULES FORMAT  [UNTIL]
+Zone  Europe/London ...                  1996
+                    0:00   EU    GMT/BST
+</pre>
+
+<p>The current time in the UK is called either Greenwich mean time or
+British summer time.</p>
+
+<p>One wrinkle, not fully explained in <code>zic.8.txt</code>, is what
+happens when switching to a named rule. To what values should
+the <code>SAVE</code> and <code>LETTER</code> data be initialized?</p>
+
+<ul>
+<li>If at least one transition has happened, use
+the <code>SAVE</code> and <code>LETTER</code> data from the most
+recent.</li>
+
+<li>If switching to a named rule before any transition has happened,
+assume standard time (<code>SAVE</code> zero), and use
+the <code>LETTER</code> data from the earliest transition with
+a <code>SAVE</code> of zero.
+
+</ul>
+
+<p>And three last things about the <code>FORMAT</code> column:</p>
+<ul>
+
+<li>The <a href="https://en.wikipedia.org/wiki/Tz_database">tz
+database</a> gives abbreviations for time zones in <i>popular
+usage</i>, which is not necessarily &ldquo;correct&rdquo; by law. For
+example, the last line in
+<code>Zone</code> <code>Pacific/Honolulu</code> (shown below) gives
+&ldquo;HST&rdquo; for &ldquo;Hawaii standard time&rdquo; even though the
+<a href="https://www.law.cornell.edu/uscode/text/15/263">legal</a>
+name for that time zone is &ldquo;Hawaii-Aleutian standard time.&rdquo;
+This author has read that there are also some places in Australia where
+popular time zone names differ from the legal ones.
+
+<li>No attempt is made to <a
+href="https://en.wikipedia.org/wiki/Internationalization_and_localization">localize</a>
+the abbreviations. They are intended to be the values returned through the
+<code>"%Z"</code> format specifier to
+<a href="https://en.wikipedia.org/wiki/C_(programming_language)">C</a>&rsquo;s
+<a href="https://pubs.opengroup.org/onlinepubs/9699919799/functions/strftime.html"><code>strftime</code></a>
+function in the
+<a href="https://kirste.userpage.fu-berlin.de/chemnet/use/info/libc/libc_19.html#SEC324">&ldquo;C&rdquo; locale</a>.
+
+<li>If there is no generally-accepted abbreviation for a time zone,
+a numeric offset is used instead, e.g., <code>+07</code> for 7 hours
+ahead of Greenwich. By convention, <code>-00</code> is used in a
+zone while uninhabited, where the offset is zero but in some sense
+the true offset is undefined.
+</ul>
+
+<p>As a final example, here&rsquo;s the complete history for Hawaii:</p>
+
+<table>
+<tr>
+  <th colspan="6">Relevant Excerpts from the US Rules</th>
+</tr>
+<tr>
+  <td colspan="6">
+    <table class="rule">
+      <tr><td style="border:none;text-align:left">
+<pre class="td">
+#Rule NAME FROM TO   -    IN  ON      AT     SAVE LETTER/S
+Rule  US   1918 1919 -    Oct lastSun  2:00  0    S
+Rule  US   1942 only -    Feb  9       2:00  1:00 W # War
+Rule  US   1945 only -    Aug 14      23:00u 1:00 P # Peace
+Rule  US   1945 only -    Sep lastSun  2:00  0    S
+</pre>
+  </td></tr></table></td>
+</tr>
+<tr>
+  <th colspan="6">The Zone Record</th>
+</tr>
+<tr>
+  <td colspan="6">
+    <table class="rule">
+      <tr><td style="border:none;text-align:left">
+<pre class="td">
+#Zone NAME            STDOFF    RULES FORMAT [UNTIL]
+Zone Pacific/Honolulu -10:31:26 -     LMT    1896 Jan 13 12:00
+                      -10:30    -     HST    1933 Apr 30  2:00
+                      -10:30    1:00  HDT    1933 May 21  2:00
+                      -10:30    US    H%sT   1947 Jun  8  2:00
+                      -10:00    -     HST
+</pre>
+  </td></tr></table></td>
+</tr>
+<tr>
+  <th colspan="6">What We Infer</th>
+</tr>
+<tr>
+  <th rowspan="2">Wall-Clock<br>Offset from<br>Prime Meridian</th>
+  <th rowspan="2">Adjust<br>Clocks</th>
+  <th colspan="2">Time Zone</th>
+  <th colspan="2">Ending at Local Time</th>
+</tr>
+<tr>
+  <th>Abbrv.</th>
+  <th>Name</th>
+  <th>Date</th>
+  <th>Time</th>
+</tr>
+<tr>
+  <td>&minus;10:31:26</td>
+  <td>&mdash;</td>
+  <td>LMT</td>
+  <td>local mean time</td>
+  <td>1896-01-13</td>
+  <td>12:00</td>
+</tr>
+<tr>
+  <td>&minus;10:30</td>
+  <td>+0:01:26</td>
+  <td>HST</td>
+  <td>Hawaii standard time</td>
+  <td>1933-04-30</td>
+  <td>02:00</td>
+</tr>
+<tr>
+  <td>&minus;9:30</td>
+  <td>+1:00</td>
+  <td>HDT</td>
+  <td>Hawaii daylight time</td>
+  <td>1933-05-21</td>
+  <td>12:00</td>
+</tr>
+<tr>
+  <td>&minus;10:30&sup1;</td>
+  <td>&minus;1:00&sup1;</td>
+  <td>HST&sup1;</td>
+  <td>Hawaii standard time</td>
+  <td>1942-02-09</td>
+  <td>02:00</td>
+</tr>
+<tr>
+  <td rowspan="2">&minus;9:30</td>
+  <td>+1:00</td>
+  <td>HWT</td>
+  <td>Hawaii war time</td>
+  <td>1945-08-14</td>
+  <td>13:30&sup2;</td>
+</tr>
+<tr>
+  <td>0</td>
+  <td>HPT</td>
+  <td>Hawaii peace time</td>
+  <td>1945-09-30</td>
+  <td rowspan="2">02:00</td>
+</tr>
+<tr>
+  <td>&minus;10:30</td>
+  <td>&minus;1:00</td>
+  <td rowspan="2">HST</td>
+  <td rowspan="2">Hawaii standard time</td>
+  <td>1947-06-08</td>
+</tr>
+<tr>
+  <td>&minus;10:00&sup3;</td>
+  <td>+0:30&sup3;</td>
+  <td colspan="2">&mdash;</td>
+</tr>
+<tr>
+  <td colspan="6" class="footnote">
+    &sup1;Switching to US rules&hellip;most recent transition (in 1919) was to standard time
+  </td>
+</tr>
+<tr>
+  <td colspan="6" class="footnote">
+    &sup2;23:00 <a href="https://en.wikipedia.org/wiki/Universal_Time">UT</a>
+    + (&minus;9:30) = 13:30 local
+  </td>
+</tr>
+<tr>
+  <td colspan="6" class="footnote">
+    &sup3;Since <a href="https://en.wikipedia.org/wiki/ISO_8601">1947&ndash;06&ndash;08T12:30Z</a>,
+    the civil time in Hawaii has been
+    <a href="https://en.wikipedia.org/wiki/Universal_Time">UT</a>/<a href="https://en.wikipedia.org/wiki/Coordinated_Universal_Time">UTC</a>
+    &minus; 10:00 year-round.
+  </td>
+</tr>
+</table>
+
+<p>There will be a short quiz later. <code>8-)</code></p>
+
+<hr>
+<address>
+This web page is in the public domain, so clarified as of
+2015-10-20 by Bill Seymour.
+<br>
+All suggestions and corrections will be welcome; all flames will be amusing.
+Mail to was at pobox dot com.
+</address>
+</body>
+</html>
diff --git a/contrib/tzcode/tz-link.html b/contrib/tzcode/tz-link.html
new file mode 100644
index 000000000000..d3b37664c71c
--- /dev/null
+++ b/contrib/tzcode/tz-link.html
@@ -0,0 +1,1175 @@
+<!DOCTYPE html>
+<html lang="en">
+<head>
+<title>Time zone and daylight saving time data</title>
+<meta charset="UTF-8">
+<style>
+pre {margin-left: 2em; white-space: pre-wrap;}
+</style>
+</head>
+<body>
+<h1>Time zone and daylight saving time data</h1>
+<p>
+<a href="https://en.wikipedia.org/wiki/Time_zone">Time zone</a> and
+<a href="https://en.wikipedia.org/wiki/Daylight_saving_time">daylight-saving</a>
+rules are controlled by individual
+governments. They are sometimes changed with little notice, and their
+histories and planned futures are often recorded only fitfully. Here
+is a summary of attempts to organize and record relevant data in this
+area.
+</p>
+  <h3>Outline</h3>
+  <nav>
+    <ul>
+      <li>The <code><abbr>tz</abbr></code> database product and process
+	<ul>
+	  <li><a href="#tzdb">The <code><abbr>tz</abbr></code> database</a></li>
+	  <li><a href="#download">Downloading the <code><abbr>tz</abbr></code> database</a></li>
+	  <li><a href="#changes">Changes to the <code><abbr>tz</abbr></code> database</a></li>
+	  <li><a href="#commentary">Commentary on the <code><abbr>tz</abbr></code> database</a></li>
+	</ul>
+      </li>
+      <li>Uses of the <code><abbr>tz</abbr></code> database
+	<ul>
+	  <li><a href="#web">Web sites using recent versions of the <code><abbr>tz</abbr></code> database</a></li>
+	  <li><a href="#protocols">Network protocols for <code><abbr>tz</abbr></code> data</a></li>
+	  <li><a href="#compilers">Other <code><abbr>tz</abbr></code> compilers</a></li>
+	  <li><a href="#TZif">Other <abbr>TZif</abbr> readers</a></li>
+	  <li><a href="#software">Other <code><abbr>tz</abbr></code>-based time zone software</a></li>
+	</ul>
+      </li>
+      <li>Related data
+	<ul>
+	  <li><a href="#other-dbs">Other time zone databases</a></li>
+	  <li><a href="#maps">Maps</a></li>
+	  <li><a href="#boundaries">Time zone boundaries</a></li>
+	</ul>
+      </li>
+      <li>Timekeeping concepts
+	<ul>
+	  <li><a href="#civil">Civil time concepts and history</a></li>
+	  <li><a href="#national">National histories of legal time</a></li>
+	  <li><a href="#costs">Costs and benefits of time shifts</a></li>
+	  <li><a href="#precision">Precision timekeeping</a></li>
+	  <li><a href="#notation">Time notation</a></li>
+	</ul>
+      </li>
+      <li><a href="#see-also">See also</a></li>
+    </ul>
+  </nav>
+
+<section>
+<h2 id="tzdb">The <code><abbr title="time zone">tz</abbr></code> database</h2>
+<p>
+The <a href="https://en.wikipedia.org/wiki/Public_domain">public-domain</a>
+time zone database contains code and data
+that represent the history of local time
+for many representative locations around the globe.
+It is updated periodically to reflect changes made by political bodies
+to time zone boundaries and daylight saving rules.
+This database (known as <code><abbr>tz</abbr></code>,
+<code><abbr>tzdb</abbr></code>, or <code>zoneinfo</code>)
+is used by several implementations,
+including
+<a href="https://www.gnu.org/software/libc/">the
+<abbr title="GNU's Not Unix">GNU</abbr>
+C Library</a> (used in
+<a href="https://en.wikipedia.org/wiki/Linux"><abbr>GNU</abbr>/Linux</a>),
+<a href="https://www.android.com">Android</a>,
+<a href="https://www.freebsd.org">Free<abbr
+title="Berkeley Software Distribution">BSD</abbr></a>,
+<a href="https://netbsd.org">Net<abbr>BSD</abbr></a>,
+<a href="https://www.openbsd.org">Open<abbr>BSD</abbr></a>,
+<a href="https://www.chromium.org/chromium-os/">Chromium OS</a>,
+<a href="https://cygwin.com">Cygwin</a>,
+<a href="https://mariadb.org">MariaDB</a>,
+<a href="https://en.wikipedia.org/wiki/MINIX">MINIX</a>,
+<a href="https://www.mysql.com">MySQL</a>,
+<a href="https://en.wikipedia.org/wiki/WebOS"><abbr
+title="Web Operating System">webOS</abbr></a>,
+<a href="https://en.wikipedia.org/wiki/IBM_AIX"><abbr
+title="Advanced Interactive eXecutive">AIX</abbr></a>,
+<a href="https://www.apple.com/ios"><abbr
+title="iPhone OS">iOS</abbr></a>,
+<a href="https://www.apple.com/macos">macOS</a>,
+<a href="https://www.microsoft.com/en-us/windows">Microsoft Windows</a>,
+<a href="https://www.vmssoftware.com">Open<abbr
+title="Virtual Memory System">VMS</abbr></a>,
+<a href="https://www.oracle.com/database/">Oracle Database</a>, and
+<a href="https://www.oracle.com/solaris">Oracle Solaris</a>.</p>
+<p>
+Each main entry in the database represents a <dfn>timezone</dfn>
+for a set of civil-time clocks that have all agreed since 1970.
+Timezones are typically identified by continent or ocean and then by the
+name of the largest city within the region containing the clocks.
+For example, <code>America/New_York</code>
+represents most of the <abbr title="United States">US</abbr> eastern time zone;
+<code>America/Phoenix</code> represents most of Arizona, which
+uses mountain time without daylight saving time (<abbr>DST</abbr>);
+<code>America/Detroit</code> represents most of Michigan, which uses
+eastern time but with different <abbr>DST</abbr> rules in 1975;
+and other entries represent smaller regions like Starke County,
+Indiana, which switched from central to eastern time in 1991
+and switched back in 2006.
+To use the database on an extended <a
+href="https://en.wikipedia.org/wiki/POSIX"><abbr
+title="Portable Operating System Interface">POSIX</abbr></a>
+implementation set the <code><abbr>TZ</abbr></code>
+environment variable to the location's full name,
+e.g., <code><abbr>TZ</abbr>="America/New_York"</code>.</p>
+<p>
+Associated with each timezone is a history of offsets from
+<a href="https://en.wikipedia.org/wiki/Universal_Time">Universal
+Time</a> (<abbr>UT</abbr>), which is <a
+href="https://en.wikipedia.org/wiki/Greenwich_Mean_Time">Greenwich Mean
+Time</a> (<abbr>GMT</abbr>) with days beginning at midnight;
+for timestamps after 1960 this is more precisely <a
+href="https://en.wikipedia.org/wiki/Coordinated_Universal_Time">Coordinated
+Universal Time</a> (<abbr>UTC</abbr>).
+The database also records when daylight saving time was in use,
+along with some time zone abbreviations such as <abbr>EST</abbr>
+for Eastern Standard Time in the <abbr>US</abbr>.</p>
+</section>
+
+<section>
+<h2 id="download">Downloading the <code><abbr>tz</abbr></code> database</h2>
+<p>
+The following <a
+href="https://en.wikipedia.org/wiki/Unix_shell">shell</a> commands download
+the latest release's two
+<a href="https://en.wikipedia.org/wiki/Tar_(computing)">tarballs</a>
+to a <abbr>GNU</abbr>/Linux or similar host.</p>
+<pre><code>mkdir tzdb
+cd tzdb
+<a href="https://www.gnu.org/software/wget/">wget</a> https://www.iana.org/time-zones/repository/tzcode-latest.tar.gz
+wget https://www.iana.org/time-zones/repository/tzdata-latest.tar.gz
+<a href="https://www.gnu.org/software/gzip/">gzip</a> -dc tzcode-latest.tar.gz | <a href="https://www.gnu.org/software/tar/">tar</a> -xf -
+gzip -dc tzdata-latest.tar.gz | tar -xf -
+</code></pre>
+<p>Alternatively, the following shell commands download the same
+release in a single-tarball format containing extra data
+useful for regression testing:</p>
+<pre><code>wget <a href="https://www.iana.org/time-zones/repository/tzdb-latest.tar.lz">https://www.iana.org/time-zones/repository/tzdb-latest.tar.lz</a>
+<a href="https://www.nongnu.org/lzip/">lzip</a> -dc tzdb-latest.tar.lz | tar -xf -
+</code></pre>
+<p>These commands use convenience links to the latest release
+of the <code><abbr>tz</abbr></code> database hosted by the
+<a href="https://www.iana.org/time-zones">Time Zone Database website</a>
+of the <a href="https://www.iana.org">Internet Assigned Numbers
+Authority (IANA)</a>.
+Older releases are in files named
+<code>tzcode<var>V</var>.tar.gz</code>,
+<code>tzdata<var>V</var>.tar.gz</code>, and
+<code>tzdb-<var>V</var>.tar.lz</code>,
+where <code><var>V</var></code> is the version.
+Since 1996, each version has been a four-digit year followed by
+lower-case letter (<samp>a</samp> through <samp>z</samp>,
+then <samp>za</samp> through <samp>zz</samp>, then <samp>zza</samp>
+through <samp>zzz</samp>, and so on).
+Since version 2022a, each release has been distributed in
+<a href="https://pubs.opengroup.org/onlinepubs/9699919799/utilities/pax.html#tag_20_92_13_06">POSIX
+ustar interchange format</a>, compressed as described above;
+older releases use a nearly-compatible format.
+Since version 2016h, each release has contained a text file named
+"<samp>version</samp>" whose first (and currently only) line is the version.
+Older releases are <a href="https://ftp.iana.org/tz/releases/">archived</a>,
+and are also available in an
+<a href="ftp://ftp.iana.org/tz/releases/"><abbr
+title="File Transfer Protocol">FTP</abbr> directory</a> via a
+less-secure protocol.</p>
+<p>Alternatively, a development repository of code and data can be
+retrieved from <a href="https://github.com">GitHub</a> via the shell
+command:</p>
+<pre><code><a href="https://git-scm.com">git</a> clone <a href="https://github.com/eggert/tz">https://github.com/eggert/tz</a>
+</code></pre>
+<p>
+Since version 2012e, each release has been tagged in development repositories.
+Untagged commits are less well tested and probably contain
+more errors.</p>
+<p>
+After obtaining the code and data files, see the
+<code>README</code> file for what to do next.
+The code lets you compile the <code><abbr>tz</abbr></code> source files into
+machine-readable binary files, one for each location. The binary files
+are in a special timezone information format (<dfn><abbr>TZif</abbr></dfn>)
+specified by <a href="https://datatracker.ietf.org/doc/html/8536">Internet
+<abbr>RFC</abbr> 8536</a>.
+The code also lets
+you read a <abbr>TZif</abbr> file and interpret timestamps for that
+location.</p>
+</section>
+
+<section>
+<h2 id="changes">Changes to the <code><abbr>tz</abbr></code> database</h2>
+<p>
+The <code><abbr>tz</abbr></code> code and data
+are by no means authoritative. If you find errors, please
+send changes to <a href="mailto:tz@iana.org"><code>tz@iana.org</code></a>,
+the time zone mailing list. You can also <a
+href="https://mm.icann.org/mailman/listinfo/tz">subscribe</a> to it
+and browse the <a
+href="https://mm.icann.org/pipermail/tz/">archive of old
+messages</a>.
+<a href="https://tzdata-meta.timtimeonline.com/">Metadata for mailing list
+discussions</a> and corresponding data changes can be
+generated <a href="https://github.com/timparenti/tzdata-meta">automatically</a>.
+</p>
+<p>
+If your government plans to change its time zone boundaries or
+daylight saving rules, inform <code>tz@iana.org</code> well in
+advance, as this will coordinate updates to many cell phones,
+computers, and other devices around the world.
+The change should be officially announced at least a year before it affects
+how clocks operate; otherwise, there is a good chance that some
+clocks will operate incorrectly after the change, due
+to delays in propagating updates to software and data. The shorter
+the notice, the more likely clock problems will arise; see "<a
+href="https://codeofmatt.com/2016/04/23/on-the-timing-of-time-zone-changes/">On
+the Timing of Time Zone Changes</a>" for examples.
+The <code><abbr>tz</abbr></code> data can represent planned changes
+far into the future, and a long-planned change can easily be reverted
+or otherwise altered with a year's notice before the change would have
+affected clocks.
+</p>
+<p>
+Changes to the <code><abbr>tz</abbr></code> code and data are often
+propagated to clients via operating system updates, so
+client <code><abbr>tz</abbr></code> data can often be corrected by
+applying these updates. With GNU/Linux and similar systems, if your
+maintenance provider has not yet adopted the
+latest <code><abbr>tz</abbr></code> data, you can often short-circuit
+the process by tailoring the generic instructions in
+the <code><abbr>tz</abbr> README</code> file and installing the latest
+data yourself. System-specific instructions for installing the
+latest <code><abbr>tz</abbr></code> data have also been published
+for <a href="https://developer.ibm.com/articles/au-aix-olson-time-zone/"><abbr>AIX</abbr></a>,
+<a
+href="https://source.android.com/devices/tech/config/timezone-rules">Android</a>,
+<a
+href="https://unicode-org.github.io/icu/userguide/datetime/timezone/"><abbr
+title="International Components for Unicode">ICU</abbr></a>,
+<a href="https://www.ibm.com/support/pages/java-sdk-time-zone-update-utility"><abbr>IBM</abbr>
+JDK</a>,
+<a href="https://www.joda.org/joda-time/tz_update.html">Joda-Time</a>, <a
+href="https://dev.mysql.com/doc/refman/en/time-zone-support.html">MySQL</a>,
+<a href="https://nodatime.org/userguide/tzdb">Noda Time</a>, and <a
+href="https://www.oracle.com/java/technologies/javase/tzupdater-readme.html">OpenJDK/Oracle JDK</a>.
+</p>
+<p>Since version 2013a,
+sources for the <code><abbr>tz</abbr></code> database have been
+<a href="https://en.wikipedia.org/wiki/UTF-8"><abbr
+title="Unicode Transformation Format 8-bit">UTF-8</abbr></a>
+<a href="https://en.wikipedia.org/wiki/Text_file">text files</a>
+with lines terminated by <a href="https://en.wikipedia.org/wiki/Newline"><abbr
+title="linefeed">LF</abbr></a>,
+which can be modified by common text editors such
+as <a href="https://www.gnu.org/software/emacs/">GNU Emacs</a>,
+<a href="https://wiki.gnome.org/Apps/Gedit">gedit</a>, and
+<a href="https://www.vim.org">vim</a>.
+Specialized source-file editing can be done via the
+<a href="https://packagecontrol.io/packages/zoneinfo">Sublime
+zoneinfo</a> package for <a
+href="https://www.sublimetext.com">Sublime Text</a> and the <a
+href="https://marketplace.visualstudio.com/items?itemName=gilmoreorless.vscode-zoneinfo">VSCode
+zoneinfo</a> extension for <a href="https://code.visualstudio.com">Visual
+Studio Code</a>.
+</p>
+<p>
+For further information about updates, please see
+<a href="https://datatracker.ietf.org/doc/html/rfc6557">Procedures for
+Maintaining the Time Zone Database</a> (Internet <abbr
+title="Request For Comments">RFC</abbr> 6557). More detail can be
+found in <a href="theory.html">Theory and pragmatics of the
+<code><abbr>tz</abbr></code> code and data</a>.
+<a href="https://a0.github.io/a0-tzmigration/">A0 TimeZone Migration</a>
+displays changes between recent <code><abbr>tzdb</abbr></code> versions.
+</p>
+</section>
+
+<section>
+<h2 id="commentary">Commentary on the <code><abbr>tz</abbr></code> database</h2>
+<ul>
+<li>The article
+<a href="https://en.wikipedia.org/wiki/Tz_database">tz database</a> is
+an encyclopedic summary.</li>
+<li><a href="tz-how-to.html">How to Read the
+tz Database Source Files</a> explains the <code><abbr>tz</abbr></code>
+database format.</li>
+<li><a
+href="https://blog.jonudell.net/2009/10/23/a-literary-appreciation-of-the-olsonzoneinfotz-database/">A
+literary appreciation of the Olson/Zoneinfo/tz database</a> comments on the
+database's style.</li>
+<li><a href="https://doi.org/10.1145/3340301.3341125">What time is it:
+managing time in the internet</a> analyzes the database longitudinally.</li>
+</ul>
+</section>
+
+<section>
+<h2 id="web">Web sites using recent versions of the
+<code><abbr>tz</abbr></code> database</h2>
+<p>
+These are listed roughly in ascending order of complexity and fanciness.
+</p>
+<ul>
+<li><a href="https://time.is">Time.is</a> shows locations'
+time and zones.</li>
+<li><a href="https://www.timejones.com">TimeJones.com</a>,
+<a href="https://timezoneconverterapp.com">Time Zone Converter</a> and
+<a href="https://www.worldclock.com">The World Clock</a>
+are time zone converters.</li>
+<li><a href="https://timezonedb.com/download">TimeZoneDB Database</a>
+publishes <code><abbr>tzdb</abbr></code>-derived data in
+<a href="https://en.wikipedia.org/wiki/Comma-separated_values"><abbr
+title="comma-separated values">CSV</abbr></a> and
+in <a href="https://en.wikipedia.org/wiki/SQL"><abbr
+title="Structured Query Language">SQL</abbr></a> form.</li>
+<li><a
+href="https://twiki.org/cgi-bin/xtra/tzdatepick.html">Date and Time Gateway</a>
+lets you see the <code><abbr>TZ</abbr></code> values directly.</li>
+<li><a
+href="https://www.convertit.com/Go/ConvertIt/World_Time/Current_Time.ASP">Current
+Time in 1000 Places</a> uses descriptions of the values.</li>
+<li><a href="https://home.kpn.nl/vanadovv/time/TZworld.html">Complete
+timezone information for all countries</a>
+displays tables of <abbr>DST</abbr> rules.
+<li><a href="https://www.timeanddate.com/worldclock/">The World Clock &ndash;
+Worldwide</a> lets you sort zone names and convert times.</li>
+<li><a href="https://24timezones.com">24TimeZones</a> has a world
+time map and a time converter.</li>
+<li><a href="https://www.zeitverschiebung.net/en/">Time Difference</a>
+calculates the current time difference between locations.</li>
+<li><a href="https://www.wx-now.com">Weather Now</a> and
+<a href="https://www.thetimenow.com">The Time Now</a> list the weather too.</li>
+</ul>
+</section>
+
+<section>
+<h2 id="protocols">Network protocols for <code><abbr>tz</abbr></code> data</h2>
+<ul>
+<li>The <a href="https://www.ietf.org">Internet Engineering Task Force</a>'s
+<a href="https://datatracker.ietf.org/wg/tzdist/charter/">Time Zone Data
+Distribution Service (tzdist) working group</a> defined <a
+href="https://datatracker.ietf.org/doc/html/rfc7808">TZDIST</a>
+(Internet <abbr>RFC</abbr> 7808), a time zone data distribution service,
+along with <a href="https://datatracker.ietf.org/doc/html/rfc7809">CalDAV</a>
+(Internet <abbr>RFC</abbr> 7809), a calendar access protocol for
+transferring time zone data by reference.
+<a href="https://devguide.calconnect.org/Time-Zones/TZDS/">TZDIST
+implementations</a> are available.
+The <a href="https://www.ietf.org/mailman/listinfo/tzdist-bis">tzdist-bis
+mailing list</a> discusses possible extensions.</li>
+<li>The <a href="https://datatracker.ietf.org/doc/html/rfc5545">
+Internet Calendaring and Scheduling Core Object Specification
+(iCalendar)</a> (Internet <abbr>RFC</abbr> 5445)
+covers time zone
+data; see its VTIMEZONE calendar component.
+The iCalendar format requires specialized parsers and generators; a
+variant <a href="https://datatracker.ietf.org/doc/html/rfc6321">xCal</a>
+(Internet <abbr>RFC</abbr> 6321) uses
+<a href="https://www.w3.org/XML/"><abbr
+title="Extensible Markup Language">XML</abbr></a> format, and a variant
+<a href="https://datatracker.ietf.org/doc/html/rfc7265">jCal</a>
+(Internet <abbr>RFC</abbr> 7265)
+uses <a href="https://www.json.org"><abbr
+title="JavaScript Object Notation">JSON</abbr></a> format.</li>
+</ul>
+</section>
+
+<section>
+<h2 id="compilers">Other <code><abbr>tz</abbr></code> compilers</h2>
+<p>Although some of these do not fully support
+<code><abbr>tz</abbr></code> data, in recent <code><abbr>tzdb</abbr></code>
+distributions you can generally work around compatibility problems by
+running the command <code>make rearguard_tarballs</code> and compiling
+from the resulting tarballs instead.</p>
+<ul>
+<li><a href="https://sourceforge.net/projects/vzic/">Vzic</a> is a <a
+href="https://en.wikipedia.org/wiki/C_%28programming_language%29">C</a>
+program that compiles
+<code><abbr>tz</abbr></code> source into iCalendar-compatible VTIMEZONE files.
+Vzic is freely
+available under the <a
+href="https://www.gnu.org/copyleft/gpl.html"><abbr>GNU</abbr>
+General Public License (<abbr
+title="General Public License">GPL</abbr>)</a>.</li>
+<li><a href="https://sourceforge.net/projects/tzical/">tziCal &ndash; tz
+database conversion utility</a> is like Vzic, except for the <a
+href="https://dotnet.microsoft.com">.NET framework</a>
+and with a <abbr>BSD</abbr>-style license.</li>
+<li><a
+href="https://metacpan.org/release/DateTime-TimeZone">DateTime::TimeZone</a>
+contains a script <code>parse_olson</code> that compiles
+<code><abbr>tz</abbr></code> source into <a href="https://www.perl.org">Perl</a>
+modules. It is part of the Perl <a
+href="https://github.com/houseabsolute/DateTime.pm/wiki">DateTime Project</a>,
+which is freely
+available under both the <abbr>GPL</abbr> and the Perl Artistic
+License. DateTime::TimeZone also contains a script
+<code>tests_from_zdump</code> that generates test cases for each clock
+transition in the <code><abbr>tz</abbr></code> database.</li>
+<li>The <a href="https://howardhinnant.github.io/date/tz.html">Time Zone
+Database Parser</a> is a
+<a href="https://en.wikipedia.org/wiki/C%2B%2B">C++</a> parser and
+runtime library with <a
+href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0355r7.html">API</a>
+adopted by
+<a href="https://en.wikipedia.org/wiki/C++20">C++20</a>,
+the current iteration of the C++ standard.
+It is freely available under the
+<abbr title="Massachusetts Institute of Technology">MIT</abbr> license.</li>
+<li><a id="ICU" href="https://icu.unicode.org">International Components for
+Unicode (<abbr>ICU</abbr>)</a> contains C/C++ and <a
+href="https://en.wikipedia.org/wiki/Java_%28programming_language%29">Java</a>
+libraries for internationalization that
+has a compiler from <code><abbr>tz</abbr></code> source
+and from <abbr title="Common Locale Data Repository">CLDR</abbr> data
+(mentioned <a href="#CLDR">below</a>)
+into an <abbr>ICU</abbr>-specific format.
+<abbr>ICU</abbr> is freely available under a
+<abbr>BSD</abbr>-style license.</li>
+<li>The <a href="https://github.com/lau/tzdata">Tzdata</a> package for
+the <a href="https://elixir-lang.org">Elixir</a> language downloads
+and compiles <code><abbr>tz</abbr></code> source and exposes <abbr
+title="Application Program Interface">API</abbr>s for use. It is
+freely available under the <abbr>MIT</abbr> license.</li>
+<li>Java-based compilers and libraries include:
+<ul>
+<li>The <a
+href="https://www.oracle.com/java/technologies/javase/tzupdater-readme.html">TZUpdater
+tool</a> compiles <code><abbr>tz</abbr></code> source into the format used by
+<a href="https://openjdk.java.net/">OpenJDK</a> and
+<a href="https://jdk.java.net/">Oracle JDK</a>.
+Although its source code is proprietary, its executable is available under the
+<a href="https://www.oracle.com/a/tech/docs/tzupdater-lic.html">Java SE
+Timezone Updater License Agreement</a>.</li>
+<li>The <a
+href="https://www.oracle.com/technetwork/articles/java/jf14-date-time-2125367.html">Java
+SE 8 Date and Time</a> <abbr>API</abbr> can be supplemented by <a
+href="https://www.threeten.org/threeten-extra/">ThreeTen-Extra</a>,
+which is freely available under a <abbr>BSD</abbr>-style license.</li>
+<li><a href="https://www.joda.org/joda-time/">Joda-Time &ndash; Java date
+and time <abbr>API</abbr></a> contains a class
+<code>org.joda.time.tz.ZoneInfoCompiler</code> that compiles
+<code><abbr>tz</abbr></code> source into a binary format. It inspired
+Java 8 <code>java.time</code>, which its users should migrate to once
+they can assume Java 8 or later. It is available under the <a
+href="https://www.apache.org/licenses/LICENSE-2.0">Apache License</a>.</li>
+<li><a href="https://bell-sw.com/pages/iana-updater/">IANA Updater</a> and <a
+href="https://www.azul.com/products/open-source-tools/ziupdater-time-zone-tool/">ZIUpdater</a>
+are alternatives to TZUpdater. IANA Updater's license is unclear;
+ZIUpdater is licensed under the <abbr>GPL</abbr>.</li>
+<li><a href="https://github.com/MenoData/Time4A">Time4A: Advanced date and
+time library for Android</a> and
+<a href="https://github.com/MenoData/Time4J/">Time4J: Advanced date,
+time and interval library for Java</a> compile
+<code><abbr>tz</abbr></code> source into a binary format.
+Time4A is available under the Apache License and Time4J is
+available under the <a
+href="https://www.gnu.org/copyleft/lesser.html"><abbr>GNU</abbr> Lesser
+General Public License (<abbr title="Lesser General Public
+License">LGPL</abbr>)</a>.</li>
+<li><abbr>ICU</abbr> (mentioned <a href="#ICU">above</a>) contains compilers and
+Java-based libraries.</li>
+</ul>
+<li><a href="https://nodatime.org">Noda Time &ndash; Date and
+time <abbr>API</abbr> for .NET</a>
+is like Joda-Time and Time4J, but for the .NET framework instead of Java.
+It is freely available under the Apache License.</li>
+<li>Many modern
+<a href="https://en.wikipedia.org/wiki/JavaScript">JavaScript</a>
+runtimes support <code><abbr>tz</abbr></code> natively via the
+<samp>timeZone</samp> option of <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Intl/DateTimeFormat"><samp>Intl.DateTimeFormat</samp></a>.
+This can be used as-is or with most of the following libraries,
+many of which also support runtimes lacking the <samp>timeZone</samp> option.
+<ul>
+<li>The <a
+href="https://github.com/formatjs/date-time-format-timezone"><samp>Intl.DateTimeFormat</samp>
+timezone polyfill</a>
+is freely available under a <abbr>BSD</abbr>-style license.</li>
+<li>The <a href="https://date-fns.org/">date-fns</a>
+library manipulates timezone-aware timestamps in browsers and
+in <a href="https://nodejs.org/en/">Node.js</a>.
+It is freely available under the <abbr>MIT</abbr> license.</li>
+<li><a href="https://github.com/iamkun/dayjs">Day.js</a> is a
+minimalist replacement for the date and time API of
+the <a href="https://momentjs.com/docs/">now-legacy Moment.js</a> date
+manipulation library.
+It is freely available under the <abbr>MIT</abbr> license.</li>
+<li><a href="https://moment.github.io/luxon/">Luxon</a> improves
+timezone support for the <samp>Intl</samp> API.
+It is freely available under the <abbr>MIT</abbr> license.</li>
+<li><a href="https://momentjs.com/timezone/">Moment Timezone</a> is a
+Moment.js plugin.
+It is freely available under the <abbr>MIT</abbr> license.</li>
+<li><a href="https://github.com/bigeasy/timezone">Timezone</a> is a
+JavaScript library that supports date arithmetic that is time zone
+aware. It is freely available under the <abbr>MIT</abbr> license.</li>
+<li><a href="https://www.npmjs.com/package/@tubular/time">@tubular/time</a>
+supports live <code><abbr>tzdb</abbr></code> updates,
+astronomical and atomic time, a command-line interface,
+and full <a
+href="https://en.wikipedia.org/wiki/TypeScript">TypeScript</a>.
+Its companion <a
+href="https://www.npmjs.com/package/@tubular/time-tzdb">@tubular/time-tzdb</a>
+can generate <abbr>TZif</abbr> and other files, and a companion website
+<a href="https://tzexplorer.org">Timezone Database Explorer</a> lets you
+convert timestamps, view transition histories, and download code and data.
+It is freely available under the <abbr>MIT</abbr> license.</li>
+</ul>
+The proposed <a
+href="https://github.com/tc39/proposal-temporal"><samp>Temporal</samp>
+objects</a> let programs access an abstract view of
+<code><abbr>tzdb</abbr></code> data, and are designed to replace <a
+href="https://codeofmatt.com/javascript-date-type-is-horribly-broken/">JavaScript's
+problematic <samp>Date</samp> objects</a> when working with dates and times.
+<li><a href="https://github.com/JuliaTime/">JuliaTime</a> contains a
+compiler from <code><abbr>tz</abbr></code> source into
+<a href="https://julialang.org/">Julia</a>. It is freely available
+under the <abbr>MIT</abbr> license.</li>
+<li><a href="https://github.com/pavkam/tzdb"><abbr>TZDB</abbr> &ndash;
+<abbr>IANA</abbr> Time Zone Database for Delphi/<abbr
+title="Free Pascal Compiler">FPC</abbr></a>
+compiles from <code><abbr>tz</abbr></code> source into
+<a href="https://en.wikipedia.org/wiki/Object_Pascal">Object Pascal</a>
+as compiled by <a href="https://en.wikipedia.org/wiki/Delphi_(IDE)">Delphi</a>
+and <a
+href="https://en.wikipedia.org/wiki/Free_Pascal"><abbr>FPC</abbr></a>.
+It is freely available under a <abbr>BSD</abbr>-style license.</li>
+<li><a href="http://pytz.sourceforge.net">pytz &ndash; World Timezone
+Definitions for Python</a> compiles <code><abbr>tz</abbr></code> source into
+<a href="https://www.python.org">Python</a>.
+It is freely available under a <abbr>BSD</abbr>-style license.
+In code that can assume Python 3.6 or later it is largely superseded; see <a
+href="https://blog.ganssle.io/articles/2018/03/pytz-fastest-footgun.html">pytz:
+The Fastest Footgun in the West</a>.</li>
+<li><a href="https://tzinfo.github.io">TZInfo &ndash;
+Ruby Timezone Library</a>
+compiles <code><abbr>tz</abbr></code> source into
+<a href="https://www.ruby-lang.org/en/">Ruby</a>.
+It is freely available under the <abbr>MIT</abbr> license.</li>
+<li>The <a href="https://www.squeaksource.com/Chronos/">Chronos Date/Time
+Library</a> is
+a <a href="https://en.wikipedia.org/wiki/Smalltalk">Smalltalk</a> class
+library that compiles <code><abbr>tz</abbr></code> source into a time
+zone repository whose format
+is either proprietary or an <abbr>XML</abbr>-encoded
+representation.</li>
+<li><a id="Tcl" href="https://tcl.tk">Tcl</a>
+contains a developer-oriented parser that compiles <code><abbr>tz</abbr></code>
+source into text files, along with a runtime that can read those
+files. Tcl is freely available under a <abbr>BSD</abbr>-style
+license.</li>
+</ul>
+</section>
+
+<section>
+<h2 id="TZif">Other <abbr>TZif</abbr> readers</h2>
+<ul>
+<li>The <a
+href="https://www.gnu.org/software/libc/"><abbr>GNU</abbr> C
+Library</a>
+has an independent, thread-safe implementation of
+a <abbr>TZif</abbr> file reader.
+This library is freely available under the LGPL
+and is widely used in <abbr>GNU</abbr>/Linux systems.</li>
+<li><a href="https://www.gnome.org">GNOME</a>'s
+<a href="https://developer.gnome.org/glib/">GLib</a> has
+a <abbr>TZif</abbr> file reader written in C that
+creates a <code>GTimeZone</code> object representing sets
+of <abbr>UT</abbr> offsets.
+It is freely available under the <abbr>LGPL</abbr>.</li>
+<li>The
+<a href="https://github.com/bloomberg/bde/wiki">BDE Standard Library</a>'s
+<code>baltzo::TimeZoneUtil</code> component contains a C++
+implementation of a <abbr>TZif</abbr> file reader. It is freely available under
+the Apache License.</li>
+<li><a href="https://github.com/google/cctz">CCTZ</a> is a simple C++
+library that translates between <abbr>UT</abbr> and civil time and
+can read <abbr>TZif</abbr> files. It is freely available under the Apache
+License.</li>
+<li><a href="https://github.com/derickr/timelib">Timelib</a> is a C
+library that reads <abbr>TZif</abbr> files and converts
+timestamps from one time zone or format to another.
+It is used by <a href="https://secure.php.net"><abbr
+title="PHP: Hypertext Preprocessor">PHP</abbr></a>,
+<a href="https://hhvm.com"><abbr title="HipHop Virtual Machine">HHVM</abbr></a>,
+and <a href="https://www.mongodb.com">MongoDB</a>.
+It is freely available under the <abbr>MIT</abbr> license.</li>
+<li>Tcl, mentioned <a href="#Tcl">above</a>, also contains a
+<abbr>TZif</abbr> file reader.</li>
+<li><a href="https://metacpan.org/pod/DateTime::TimeZone::Tzfile">
+DateTime::TimeZone::Tzfile</a>
+is a <abbr>TZif</abbr> file reader written in Perl.
+It is freely available under the same terms as Perl
+(dual <abbr>GPL</abbr> and Artistic license).</li>
+<li>Python has a <a id="python-zoneinfo"
+href="https://docs.python.org/3/library/zoneinfo.html"><code>zoneinfo.ZoneInfo</code>
+class</a> that reads <abbr>TZif</abbr> data and creates objects
+that represent <code><abbr>tzdb</abbr></code> timezones.
+Python is freely available under the
+<a href="https://docs.python.org/3/license.html">Python Software Foundation
+License</a>.
+A companion <a id="pypi-tzdata" href="https://pypi.org/">PyPI</a> module
+<a href="https://pypi.org/project/tzdata/"><code>tzdata</code></a>
+supplies TZif data if the underlying system data cannot be found;
+it is freely available under the Apache License.</li>
+<li>The
+public-domain <a href="https://github.com/dbaron/tz.js">tz.js</a>
+library contains a Python tool that
+converts <abbr>TZif</abbr> data into
+<abbr>JSON</abbr>-format data suitable for use
+in its JavaScript library for time zone conversion. Dates before 1970
+are not supported.</li>
+<li>The <a
+href="https://hackage.haskell.org/package/timezone-olson">timezone-olson</a>
+package contains <a href="https://www.haskell.org">Haskell</a> code that
+parses and uses <abbr>TZif</abbr> data. It is freely
+available under a <abbr>BSD</abbr>-style license.</li>
+</ul>
+</section>
+
+<section>
+<h2 id="software">Other <code><abbr>tz</abbr></code>-based time zone software</h2>
+<ul>
+<li><a href="https://foxclocks.org">FoxClocks</a>
+is an extension for <a href="https://www.google.com/chrome/">Google
+Chrome</a> and for <a
+href="https://wiki.mozilla.org/Modules/Toolkit">Mozilla
+Toolkit</a> applications like <a
+href="https://www.mozilla.org/en-US/firefox/new/">Firefox</a> and <a
+href="https://www.mozilla.org/en-US/thunderbird/">Thunderbird</a>.
+It displays multiple clocks in the application window, and has a mapping
+interface to <a href="https://www.google.com/earth/">Google Earth</a>.
+It is freely available under the <abbr>GPL</abbr>.</li>
+<li><a href="https://golang.org">Go programming language</a>
+implementations contain a copy of a 32-bit subset of a recent
+<code><abbr>tz</abbr></code> database in a
+Go-specific format.</li>
+<li>Microsoft Windows 8.1
+and later has <code><abbr>tz</abbr></code> data and <abbr>CLDR</abbr>
+data (mentioned <a href="#CLDR">below</a>) used by the
+<a href="https://en.wikipedia.org/wiki/Windows_Runtime">Windows Runtime</a> /
+<a href="https://en.wikipedia.org/wiki/Universal_Windows_Platform">Universal Windows Platform</a> classes
+<a href="https://docs.microsoft.com/uwp/api/Windows.Globalization.DateTimeFormatting.DateTimeFormatter"><code>DateTimeFormatter</code></a> and
+<a href="https://docs.microsoft.com/uwp/api/windows.globalization.calendar"><code>Calendar</code></a>.
+<a id="System.TimeZoneInfo"
+href="https://blogs.msdn.microsoft.com/bclteam/2007/06/07/exploring-windows-time-zones-with-system-timezoneinfo-josh-free/">Exploring
+Windows Time Zones with <code>System.TimeZoneInfo</code></a> describes
+the older, proprietary method of Microsoft Windows 2000 and later,
+which stores time zone data in the
+<a href="https://en.wikipedia.org/wiki/Windows_Registry">Windows Registry</a>. The
+<a
+href="https://unicode.org/cldr/charts/latest/supplemental/zone_tzid.html">Zone &rarr;
+Tzid table</a> or <a
+href="https://github.com/unicode-org/cldr/blob/master/common/supplemental/windowsZones.xml"><abbr>XML</abbr>
+file</a> of the <abbr>CLDR</abbr> data maps proprietary zone IDs
+to <code><abbr>tz</abbr></code> names.
+These mappings can be performed programmatically via the <a href="https://github.com/mj1856/TimeZoneConverter">TimeZoneConverter</a> .NET library,
+or the ICU Java and C++ libraries mentioned <a href="#ICU">above</a>.
+<li><a
+href="https://www.oracle.com/java/index.html">Oracle
+Java</a> contains a copy of a subset of a recent
+<code><abbr>tz</abbr></code> database in a
+Java-specific format.</li>
+</ul>
+</section>
+
+<section>
+<h2 id="other-dbs">Other time zone databases</h2>
+<ul>
+<li><a href="https://www.astro.com/atlas">Time-zone Atlas</a>
+is Astrodienst's Web version of Shanks and Pottenger's out-of-print
+time zone history atlases
+<a href="https://www.worldcat.org/oclc/468828649">for the US</a> and
+<a href="https://www.worldcat.org/oclc/76950459">for the world</a>.
+Although these extensive atlases
+<a href="https://astrologynewsservice.com/opinion/how-astrologers-contributed-to-the-information-age-a-brief-history-of-time/">were
+sources for much of the older <code><abbr>tz</abbr></code> data</a>,
+they are unreliable as Shanks appears to have
+guessed many <abbr>UT</abbr> offsets and transitions. The atlases cite no
+sources and do not indicate which entries are guesswork.</li>
+<li><a href="https://en.wikipedia.org/wiki/HP-UX">HP-UX</a> has a database in
+its own <code>tztab</code>(4) format.</li>
+<li>Microsoft Windows has proprietary data mentioned
+<a href="#System.TimeZoneInfo">above</a>.</li>
+<li><a href="https://www.worldtimeserver.com">World Time Server</a>
+is another time zone database.</li>
+<li>The <a
+href="https://www.iata.org/publications/store/Pages/standard-schedules-information.aspx">Standard
+Schedules Information Manual</a> of the
+International Air Transport Association
+gives current time zone rules for airports served by commercial aviation.</li>
+</ul>
+</section>
+
+<section>
+<h2 id="maps">Maps</h2>
+<ul>
+<li>The <a
+href="https://www.cia.gov/the-world-factbook/maps/world-regional/">World
+and Regional Maps section</a> of <em>The World Factbook</em>, published by the
+<a href="https://www.cia.gov">US Central Intelligence
+Agency (<abbr
+title="Central Intelligence Agency">CIA</abbr>)</a>, contains a time
+zone map; the
+<a
+href="https://legacy.lib.utexas.edu/maps/world.html">Perry&ndash;Casta&ntilde;eda
+Library Map Collection</a>
+of the University of Texas at Austin has copies of
+recent editions.
+The pictorial quality is good,
+but the maps do not indicate daylight saving time,
+and parts of the data are a few years out of date.</li>
+<li><a href="https://www.worldtimezone.com">World Time Zone Map
+with current time</a>
+has several fancy time zone maps; it covers Russia particularly well.
+The maps' pictorial quality is not quite as good as the
+<abbr>CIA</abbr>'s
+but the maps are more up to date.</li>
+<li><a
+href="https://blog.poormansmath.net/how-much-is-time-wrong-around-the-world/">How
+much is time wrong around the world?</a> maps the difference between
+mean solar and standard time, highlighting areas such as western China
+where the two differ greatly. It's a bit out of date, unfortunately.</li>
+</ul>
+</section>
+
+<section>
+<h2 id="boundaries">Time zone boundaries</h2>
+<p>Geographical boundaries between timezones are available
+from several <a
+href="https://en.wikipedia.org/wiki/Internet_geolocation">Internet
+geolocation</a>
+services and other sources.</p>
+<ul>
+<li><a href="https://github.com/evansiroky/timezone-boundary-builder">Timezone
+Boundary Builder</a> extracts
+<a href="https://www.openstreetmap.org">Open Street Map</a> data to build
+boundaries of <code><abbr>tzdb</abbr></code> timezones.
+Its code is freely available under the <abbr>MIT</abbr> license, and
+its data entries are freely available under the
+<a href="https://opendatacommons.org/licenses/odbl/">Open Data Commons
+Open Database License</a>. The maps' borders appear to be quite accurate.</li>
+<li>Programmatic interfaces that map geographical coordinates via tz_world to
+<code><abbr>tzdb</abbr></code> timezones include:
+<ul>
+<li><a href="https://github.com/mj1856/GeoTimeZone">GeoTimeZone</a> is
+written in <a
+href="https://en.wikipedia.org/wiki/C_Sharp_(programming_language)">C#</a>
+and is freely available under the <abbr>MIT</abbr> license.</li>
+<li>The <a href="https://github.com/bradfitz/latlong">latlong package</a>
+is written in Go and is freely available under the Apache License.</li>
+<li><a href="https://github.com/drtimcooper/LatLongToTimezone">LatLongToTimezone</a>,
+in both Java and
+<a href="https://en.wikipedia.org/wiki/Swift_(programming_language)">Swift</a>
+form, is freely available under the MIT license.</li>
+<li>For Node.js,
+the <a href="https://www.npmjs.com/package/geo-tz">geo-tz module</a>
+is freely available under the MIT license, and
+the <a href="https://www.npmjs.com/package/tz-lookup">tz-lookup module</a>
+is in the public domain.</li>
+<li>The <a
+href="https://github.com/MrMinimal64/timezonefinder">timezonefinder</a>
+library for Python is freely available under the MIT license.
+<li>The <a
+href="https://github.com/gunyarakun/timezone_finder">timezone_finder</a>
+library for Ruby is freely available under the MIT license.</li>
+</ul></li>
+<li>Free access via a network API, if you register a key, is provided by
+the <a
+href="https://www.geonames.org/export/web-services.html#timezone">GeoNames
+Timezone web service</a>, the <a
+href="https://developers.google.com/maps/documentation/timezone/intro">Google
+Maps Time Zone API</a>, and
+the <a href="https://timezonedb.com/api">TimeZoneDB API</a>.
+Commercial network API access is provided
+by <a href="https://askgeo.com">AskGeo</a>
+and <a href="https://www.geogarage.com/blog/news-1/post/geogarage-time-zone-api-31">GeoGarage</a>.
+</li>
+<li>"<a
+href="https://stackoverflow.com/questions/16086962/how-to-get-a-time-zone-from-a-location-using-latitude-and-longitude-coordinates/16086964">How
+to get a time zone from a location using latitude and longitude
+coordinates?</a>" discusses other geolocation possibilities.</li>
+<li><a href="http://statoids.com/statoids.html">Administrative
+Divisions of Countries ("Statoids")</a> lists
+political subdivision data related to time zones.</li>
+<li><a href="https://home.kpn.nl/vanadovv/time/Multizones.html">Time
+zone boundaries for multizone countries</a> summarizes legal
+boundaries between time zones within countries.</li>
+<li><a href="https://manifold.net/info/freestuff.shtml">Manifold Software
+&ndash; GIS and Database Tools</a> includes a Manifold-format map of
+world time zone boundaries distributed under the
+<abbr>GPL</abbr>.</li>
+<li>A ship within the <a
+href="https://en.wikipedia.org/wiki/Territorial_waters">territorial
+waters</a> of any nation uses that nation's time. In international
+waters, time zone boundaries are meridians 15&deg; apart, except that
+<abbr>UT</abbr>&minus;12 and <abbr>UT</abbr>+12 are each 7.5&deg;
+wide and are separated by
+the 180&deg; meridian (not by the International Date Line, which is
+for land and territorial waters only). A captain can change ship's
+clocks any time after entering a new time zone; midnight changes are
+common.</li>
+</ul>
+</section>
+
+<section>
+<h2 id="civil">Civil time concepts and history</h2>
+<ul>
+<li><a href="https://www.nist.gov/pml/time-and-frequency-division/popular-links/walk-through-time">A
+Walk through Time</a>
+surveys the evolution of timekeeping.</li>
+<li>The history of daylight saving time is surveyed in <a
+href="http://www.webexhibits.org/daylightsaving/">About Daylight
+Saving Time &ndash; History, rationale, laws &amp; dates</a> and summarized in
+<a href="http://seizethedaylight.com/dst/">A Brief
+History of Daylight Saving Time</a>.</li>
+<li><a href="https://www.laphamsquarterly.org/roundtable/time-lords">Time
+Lords</a> discusses how authoritarians manipulate civil time.</li>
+<li><a href="https://www.w3.org/TR/timezone/">Working with Time Zones</a>
+contains guidelines and best practices for software applications that
+deal with civil time.</li>
+<li><a href="https://www.staff.science.uu.nl/~gent0113/idl/idl.htm">A History of
+the International Date Line</a> tells the story of the most important
+time zone boundary.</li>
+<li><a href="http://statoids.com/tconcept.html">Basic Time
+Zone Concepts</a> discusses terminological issues behind time zones.</li>
+</ul>
+</section>
+
+<section>
+<h2 id="national">National histories of legal time</h2>
+<dl>
+<dt>Australia</dt>
+<dd>The Parliamentary Library commissioned a <a
+href="https://www.aph.gov.au/binaries/library/pubs/rp/2009-10/10rp10.pdf">research
+paper on daylight saving time in Australia</a>.
+The Bureau of Meteorology publishes a list of <a
+href="http://www.bom.gov.au/climate/averages/tables/dst_times.shtml">Implementation
+Dates of Daylight Savings Time within Australia</a>.</dd>
+<dt>Belgium</dt>
+<dd>The Royal Observatory of Belgium maintains a table of time in
+Belgium (in
+<a href="https://www.astro.oma.be/GENERAL/INFO/nli001a.html"
+hreflang="nl">Dutch</a> and <a
+href="https://www.astro.oma.be/GENERAL/INFO/fri001a.html"
+hreflang="fr">French</a>).</dd>
+<dt>Brazil</dt>
+<dd>The Time Service Department of the National Observatory
+records <a href="http://pcdsh01.on.br/DecHV.html"
+hreflang="pt-BR">Brazil's daylight saving time decrees (in
+Portuguese)</a>.</dd>
+<dt>Canada</dt>
+<dd>National Research Council Canada publishes current
+and some older information about <a
+href="https://nrc.canada.ca/en/certifications-evaluations-standards/canadas-official-time/time-zones-daylight-saving-time">time
+zones and daylight saving time</a>.</dd>
+<dt>Chile</dt>
+<dd>The Hydrographic and Oceanographic Service of the Chilean Navy publishes a
+<a href="https://www.horaoficial.cl/historia_hora.php" hreflang="es">history of
+Chile's official time (in Spanish)</a>.</dd>
+<dt>China</dt>
+<dd>The Hong Kong Observatory maintains a
+<a href="https://www.hko.gov.hk/en/gts/time/Summertime.htm">history of
+ summer time in Hong Kong</a>,
+and Macau's Meteorological and Geophysical Bureau maintains a <a
+href="https://www.smg.gov.mo/en/subpage/224/page/174">similar
+history for Macau</a>.
+Unfortunately the latter is incomplete and has errors.</dd>
+<dt>Czech Republic</dt>
+<dd><a href="https://kalendar.beda.cz/kdy-zacina-a-konci-letni-cas"
+hreflang="cs">When daylight saving time starts and ends (in Czech)</a>
+summarizes and cites historical <abbr>DST</abbr> regulations.</dd>
+<dt>Germany</dt>
+<dd>The National Institute for Science and Technology maintains the <a
+href="https://www.ptb.de/cms/en/fachabteilungen/abt4/fb-44/ag-441/realisation-of-legal-time-in-germany.html">Realisation
+of Legal Time in Germany</a>.</dd>
+<dt>Israel</dt>
+<dd>The Interior Ministry periodically issues <a
+href="ftp://ftp.cs.huji.ac.il/pub/tz/announcements"
+hreflang="he">announcements (in Hebrew)</a>.</dd>
+<dt>Malaysia</dt>
+<dd>See Singapore <a href="#Singapore">below</a>.</dd>
+<dt>Mexico</dt>
+<dd>The Investigation and Analysis Service of the Mexican Library of
+Congress has published a <a
+href="https://www.diputados.gob.mx/bibliot/publica/inveyana/polisoc/horver/index.htm"
+hreflang="es">history of Mexican local time (in Spanish)</a>.</dd>
+<dt>Netherlands</dt>
+<dd><a href="https://www.staff.science.uu.nl/~gent0113/wettijd/wettijd.htm"
+hreflang="nl">Legal time in the Netherlands (in Dutch)</a>
+covers the history of local time in the Netherlands from ancient times.</dd>
+<dt>New Zealand</dt>
+<dd>The Department of Internal Affairs maintains a brief <a
+href="https://www.dia.govt.nz/Daylight-Saving-History">History of
+Daylight Saving</a>.</dd>
+<dt>Portugal</dt>
+<dd>The Lisbon Astronomical Observatory publishes a
+<a href="https://oal.ul.pt/hora-legal/" hreflang="pt">history of
+legal time (in Portuguese)</a>.</dd>
+<dt>Singapore</dt>
+<dd><a id="Singapore"
+href="https://web.archive.org/web/20190822231045/http://www.math.nus.edu.sg/~mathelmr/teaching/timezone.html">Why
+is Singapore in the "Wrong" Time Zone?</a> details the
+history of legal time in Singapore and Malaysia.</dd>
+<dt>United Kingdom</dt>
+<dd><a
+href="https://www.polyomino.org.uk/british-time/">History of
+legal time in Britain</a> discusses in detail the country
+with perhaps the best-documented history of clock adjustments.</dd>
+<dt>United States</dt>
+<dd>The Department of Transportation's <a
+href="https://www.transportation.gov/regulations/recent-time-zone-proceedings">Recent
+Time Zone Proceedings</a> lists changes to time zone boundaries.</dd>
+<dt>Uruguay</dt>
+<dd>The Oceanography, Hydrography, and Meteorology Service of the Uruguayan
+Navy (SOHMA) publishes an annual <a
+href="https://sohma.armada.mil.uy/index.php/servicios/datos-astronomicos" hreflang="es">almanac
+(in Spanish)</a>.</dd>
+</dl>
+</section>
+
+<section>
+<h2 id="costs">Costs and benefits of time shifts</h2>
+<p>Various sources argue for and against daylight saving time and time
+zone shifts, and many scientific studies have been conducted. This
+section summarizes reviews and position statements based on
+scientific literature in the area.</p>
+<ul>
+<li>Carey RN, Sarma KM.
+<a href="https://bmjopen.bmj.com/content/7/6/e014319.long">Impact of
+daylight saving time on road traffic collision risk: a systematic
+review</a>.
+<em>BMJ Open.</em> 2017;7(6):e014319. doi:<a href="https://doi.org/10.1136/bmjopen-2016-014319">10.1136/bmjopen-2016-014319</a>.
+This reviews research literature and concludes that the evidence
+neither supports nor refutes road safety benefits from
+shifts in time zones.</li>
+<li>Havranek T, Herman D, Irsova D.
+<a href="https://www.iaee.org/en/publications/ejarticle.aspx?id=3051">Does
+daylight saving save electricity? A meta-analysis.</a>
+<em>Energy J.</em> 2018;39(2):35&ndash;61.
+doi:<a href="https://doi.org/10.5547/01956574.39.2.thav">10.5547/01956574.39.2.thav</a>.
+This analyzes research literature and concludes, "Electricity savings
+are larger for countries farther away from the equator, while
+subtropical regions consume more electricity because of <abbr>DST</abbr>."</li>
+<li>Rishi MA, Ahmed O, Barrantes Perez JH <em>et al</em>.
+<a href="https://jcsm.aasm.org/doi/10.5664/jcsm.8780">Daylight saving time:
+an American Academy of Sleep Medicine position statement</a>.
+<em>J Clin Sleep Med.</em>
+2020;<a href="https://doi.org/10.5664/jcsm.8780">10.5664/jcsm.8780</a>.
+This argues for permanent standard time due to health risks of both
+<abbr>DST</abbr> transitions and permanent <abbr>DST</abbr>.</li>
+<li>Roenneberg T, Wirz-Justice A, Skene DJ <em>et al</em>.
+<a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7205184/">Why
+should we abolish Daylight Saving Time?</a>
+<em>J Biol Rhythms</em>. 2019;34(3):227&ndash;230.
+doi:<a href="https://doi.org/10.1177/0748730419854197">10.1177/0748730419854197</a>.
+This position paper of the Society for Research on Biological Rhythms
+opposes DST changes and permanent DST, and advocates that governments adopt
+"permanent Standard Time for the health and safety of their citizens".</li>
+</ul>
+</section>
+
+<section>
+<h2 id="precision">Precision timekeeping</h2>
+<ul>
+<li><a
+href="http://leapsecond.com/hpan/an1289.pdf">The
+Science of Timekeeping</a> is a thorough introduction
+to the theory and practice of precision timekeeping.</li>
+<li><a href="https://doi.org/10.1007/978-3-319-59909-0">The Science of
+Time 2016</a> contains several freely-readable papers.</li>
+<li><a href="https://www.ntp.org"><abbr
+title="Network Time Protocol">NTP</abbr>: The Network
+Time Protocol</a> (Internet <abbr>RFC</abbr> 5905)
+discusses how to synchronize clocks of
+Internet hosts.</li>
+<li>The <a href="https://www.usenix.org/system/files/conference/nsdi18/nsdi18-geng.pdf"><span style="font-variant: small-caps">Huygens</span></a>
+family of software algorithms can achieve accuracy to a few tens of
+nanoseconds in scalable server farms without special hardware.</li>
+<li>The <a
+href="https://www.nist.gov/intelligent-systems-division/ieee-1588">Precision
+Time Protocol</a> (<abbr
+title="Institute of Electrical and Electronics Engineers">IEEE</abbr> 1588)
+can achieve submicrosecond clock accuracy on a local area network
+with special-purpose hardware.</li>
+<li><a
+href="https://datatracker.ietf.org/doc/html/rfc4833">Timezone
+Options for <abbr title="Dynamic Host Configuration Protocol">DHCP</abbr></a>
+(Internet <abbr>RFC</abbr> 4833)
+specifies a <a
+href="https://en.wikipedia.org/wiki/Dynamic_Host_Configuration_Protocol"><abbr>DHCP</abbr></a>
+option for a server to configure
+a client's time zone and daylight saving settings automatically.</li>
+<li><a href="https://www.ucolick.org/~sla/leapsecs/timescales.html">Time
+Scales</a> describes astronomical time scales like
+<abbr title="Terrestrial Dynamic Time">TDT</abbr>,
+<abbr title="Geocentric Coordinate Time">TCG</abbr>, and
+<abbr title="Barycentric Dynamic Time">TDB</abbr>.
+<li>The <a href="https://www.iau.org"><abbr
+title="International Astronomical Union">IAU</abbr></a>'s <a
+href="https://www.iausofa.org"><abbr
+title="Standards Of Fundamental Astronomy">SOFA</abbr></a>
+collection contains C and <a
+href="https://en.wikipedia.org/wiki/Fortran">Fortran</a>
+code for converting among time scales like
+<abbr title="International Atomic Time">TAI</abbr>,
+<abbr>TDB</abbr>, <abbr>TDT</abbr> and
+<abbr>UTC</abbr>. It is freely available under the
+<a href="https://www.iausofa.org/tandc.html">SOFA license</a>.</li>
+<li><a
+href="https://www.giss.nasa.gov/tools/mars24/help/notes.html">Mars24 Sunclock
+&ndash; Time on Mars</a> describes Airy Mean Time (<abbr>AMT</abbr>) and the
+diverse local time
+scales used by each landed mission on Mars.</li>
+<li><a href="http://leapsecond.com">LeapSecond.com</a> is
+dedicated not only to leap seconds but to precise time and frequency
+in general. It covers the state of the art in amateur timekeeping, and
+how the art has progressed over the past few decades.</li>
+<li>The rules for leap seconds are specified in Annex 1 (Time scales) of <a
+href="https://www.itu.int/rec/R-REC-TF.460-6-200202-I/">Standard-frequency
+and time-signal emissions</a>, International Telecommunication Union &ndash;
+Radiocommunication Sector (ITU-R) Recommendation TF.460-6 (02/2002).</li>
+<li><a
+href="https://www.iers.org/IERS/EN/Publications/Bulletins/bulletins.html"><abbr
+title="International Earth Rotation and Reference Systems Service">IERS</abbr>
+Bulletins</a> contains official publications of the International
+Earth Rotation and Reference Systems Service, which decides when leap
+seconds occur. The <code><abbr>tz</abbr></code> code and data support leap seconds
+via an optional "<code>right</code>" configuration where a computer's internal
+<code>time_t</code> integer clock counts every <abbr>TAI</abbr> second,
+as opposed to the default "<code>posix</code>" configuration
+where the internal clock ignores leap seconds.
+The two configurations agree for timestamps starting with 1972-01-01 00:00:00
+<abbr>UTC</abbr> (<code>time_t</code> 63&thinsp;072&thinsp;000) and diverge for
+timestamps starting with <code>time_t</code> 78&thinsp;796&thinsp;800,
+which corresponds to the first leap second
+1972-06-30 23:59:60 <abbr>UTC</abbr> in the "<code>right</code>" configuration,
+and to
+1972-07-01 00:00:00 <abbr>UTC</abbr> in the "<code>posix</code>" configuration.
+In practice the two configurations also agree for timestamps before
+1972 even though the historical situation is messy, partly because
+neither <abbr>UTC</abbr> nor <abbr>TAI</abbr>
+is well-defined for sufficiently-old timestamps.</li>
+<li><a href="https://developers.google.com/time/smear">Leap Smear</a>
+discusses how to gradually adjust <abbr>POSIX</abbr> clocks near a
+leap second so that they disagree with <abbr>UTC</abbr> by at most a
+half second, even though every <abbr>POSIX</abbr> minute has exactly
+sixty seconds. This approach works with the default <code><abbr>tz</abbr></code>
+"<code>posix</code>" configuration, is <a
+href="http://bk1.ntp.org/ntp-stable/README.leapsmear">supported</a> by
+the <abbr>NTP</abbr> reference implementation, <a
+href="https://github.com/google/unsmear">supports</a> conversion between
+<abbr>UTC</abbr> and smeared <abbr>POSIX</abbr> timestamps, and is used by major
+cloud service providers. However, according to
+<a href="https://datatracker.ietf.org/doc/html/rfc8633#section-3.7.1">&sect;3.7.1 of
+Network Time Protocol Best Current Practices</a>
+(Internet <abbr>RFC</abbr> 8633), leap smearing is not suitable for
+applications requiring accurate <abbr>UTC</abbr> or civil time,
+and is intended for use only in single, well-controlled environments.</li>
+<li>The <a
+href="https://pairlist6.pair.net/mailman/listinfo/leapsecs">Leap
+Second Discussion List</a> covers <a
+href="https://www2.unb.ca/gge/Resources/gpsworld.november99.pdf">McCarthy
+and Klepczynski's 1999 proposal to discontinue leap seconds</a>,
+discussed further in
+<a href="https://www.cl.cam.ac.uk/~mgk25/time/metrologia-leapsecond.pdf">The
+leap second: its history and possible future</a>.
+<a href="https://www.ucolick.org/~sla/leapsecs/"><abbr>UTC</abbr>
+might be redefined
+without Leap Seconds</a> gives pointers on this
+contentious issue, which was active until 2015 and could become active
+again.</li>
+</ul>
+</section>
+
+<section>
+<h2 id="notation">Time notation</h2>
+<ul>
+<li>The <a id="CLDR" href="https://cldr.unicode.org">Unicode Common Locale Data
+Repository (<abbr>CLDR</abbr>) Project</a> has localizations for time
+zone names, abbreviations, identifiers, and formats. For example, it
+contains French translations for "Eastern European Summer Time",
+"<abbr title="Eastern European Summer Time">EEST</abbr>", and
+"Bucharest". Its
+<a href="https://unicode.org/cldr/charts/latest/by_type/">by-type
+charts</a> show these values for many locales. Data values are available in
+both <abbr title="Locale Data Markup Language">LDML</abbr>
+(an <abbr>XML</abbr> format) and <abbr>JSON</abbr>.
+<li>
+<a href="https://www.cl.cam.ac.uk/~mgk25/iso-time.html">A summary of
+the international standard date and time notation</a> covers
+<a
+href="https://www.iso.org/standard/70907.html"><em><abbr
+title="International Organization for Standardization">ISO</abbr>
+8601-1:2019 &ndash; Date and time &ndash; Representations for information
+interchange &ndash; Part 1: Basic rules</em></a>.</li>
+<li>
+<a href="https://www.w3.org/TR/xmlschema/#dateTime"><abbr>XML</abbr>
+Schema: Datatypes &ndash; dateTime</a> specifies a format inspired by
+<abbr>ISO</abbr> 8601 that is in common use in <abbr>XML</abbr> data.</li>
+<li><a href="https://datatracker.ietf.org/doc/html/rfc5322#section-3.3">&sect;3.3 of
+Internet Message Format</a> (Internet <abbr>RFC</abbr> 5322)
+specifies the time notation used in email and <a
+href="https://en.wikipedia.org/wiki/Hypertext_Transfer_Protocol"><abbr>HTTP</abbr></a>
+headers.</li>
+<li>
+<a href="https://datatracker.ietf.org/doc/html/rfc3339">Date and Time
+on the Internet: Timestamps</a> (Internet <abbr>RFC</abbr> 3339)
+specifies an <abbr>ISO</abbr> 8601
+profile for use in new Internet
+protocols.</li>
+<li>
+<a href="https://web.archive.org/web/20190130042457/https://www.hackcraft.net/web/datetime/">Date &amp; Time
+Formats on the Web</a> surveys web- and Internet-oriented date and time
+formats.</li>
+<li>Alphabetic time zone abbreviations should not be used as unique
+identifiers for <abbr>UT</abbr> offsets as they are ambiguous in
+practice. For example, in English-speaking North America
+"<abbr>CST</abbr>" denotes 6 hours behind <abbr>UT</abbr>,
+but in China it denotes 8 hours ahead of <abbr>UT</abbr>,
+and French-speaking North Americans prefer
+"<abbr title="Heure Normale du Centre">HNC</abbr>" to
+"<abbr>CST</abbr>". The <code><abbr>tz</abbr></code>
+database contains English abbreviations for many timestamps;
+unfortunately some of these abbreviations were merely the database maintainers'
+inventions, and these have been removed when possible.</li>
+<li>Numeric time zone abbreviations typically count hours east of
+<abbr>UT</abbr>, e.g., +09 for Japan and
+&minus;10 for Hawaii. However, the <abbr>POSIX</abbr>
+<code><abbr>TZ</abbr></code> environment variable uses the opposite convention.
+For example, one might use <code><abbr>TZ</abbr>="<abbr
+title="Japan Standard Time">JST</abbr>-9"</code> and
+<code><abbr>TZ</abbr>="<abbr title="Hawaii Standard Time">HST</abbr>10"</code>
+for Japan and Hawaii, respectively. If the
+<code><abbr>tz</abbr></code> database is available, it is usually better to use
+settings like <code><abbr>TZ</abbr>="Asia/Tokyo"</code> and
+<code><abbr>TZ</abbr>="Pacific/Honolulu"</code> instead, as this should avoid
+confusion, handle old timestamps better, and insulate you better from
+any future changes to the rules. One should never set
+<abbr>POSIX</abbr> <code><abbr>TZ</abbr></code> to a value like
+<code>"GMT-9"</code>, though, since this would incorrectly imply that
+local time is nine hours ahead of <abbr>UT</abbr> and the time zone
+is called "<abbr>GMT</abbr>".</li>
+</ul>
+</section>
+
+<section>
+<h2 id="see-also">See also</h2>
+<ul>
+<li><a href="theory.html">Theory and pragmatics of the
+<code><abbr>tz</abbr></code> code and data</a></li>
+<li><a href="tz-art.html">Time and the Arts</a></li>
+</ul>
+</section>
+
+<footer>
+<hr>
+This web page is in the public domain, so clarified as of
+2009-05-17 by Arthur David Olson.
+<br>
+Please send corrections to this web page to the
+<a href="mailto:tz@iana.org">time zone mailing list</a>.
+</footer>
+</body>
+</html>
diff --git a/contrib/tzcode/tzfile.5 b/contrib/tzcode/tzfile.5
new file mode 100644
index 000000000000..b53abaab18d6
--- /dev/null
+++ b/contrib/tzcode/tzfile.5
@@ -0,0 +1,492 @@
+.\" This file is in the public domain, so clarified as of
+.\" 1996-06-05 by Arthur David Olson.
+.\"
+.\" $FreeBSD$
+.\"
+.Dd December 15, 2022
+.Dt TZFILE 5
+.Os
+.Sh NAME
+.Nm tzfile
+.Nd timezone information
+.Sh DESCRIPTION
+The timezone information files used by
+.Xr tzset 3
+are found under
+.Pa /usr/share/zoneinfo .
+These files use the format described in Internet RFC 8536.
+Each file is a sequence of 8-bit bytes.
+In a file, a binary integer is represented by a sequence of one or
+more bytes in network order (bigendian, or high-order byte first),
+with all bits significant,
+a signed binary integer is represented using two's complement,
+and a boolean is represented by a one-byte binary integer that is
+either 0 (false) or 1 (true).
+The format begins with a 44-byte header containing the following fields:
+.Pp
+.Bl -bullet
+.It
+The magic four-byte ASCII sequence
+.Dq "TZif"
+identifies the file as a timezone information file.
+.It
+A byte identifying the version of the file's format
+(as of 2021, either an ASCII NUL,
+.Dq "2" ,
+.Dq "3" ,
+or
+.Dq "4" ) .
+.It
+Fifteen bytes containing zeros reserved for future use.
+.It
+Six four-byte integer values, in the following order:
+.Pp
+.Bl -tag -compat -width tzh_ttisstdcnt
+.It Va tzh_ttisutcnt
+The number of UT/local indicators stored in the file.
+(UT is Universal Time.)
+.It Va tzh_ttisstdcnt
+The number of standard/wall indicators stored in the file.
+.It Va tzh_leapcnt
+The number of leap seconds for which data entries are stored in the file.
+.It Va tzh_timecnt
+The number of transition times for which data entries are stored
+in the file.
+.It Va tzh_typecnt
+The number of local time types for which data entries are stored
+in the file (must not be zero).
+.It Va tzh_charcnt
+The number of bytes of time zone abbreviation strings
+stored in the file.
+.El
+.El
+.Pp
+The above header is followed by the following fields, whose lengths
+depend on the contents of the header:
+.Bl -tag -compat -width tzh_timecnt
+.It Va tzh_timecnt
+four-byte signed integer values sorted in ascending order.
+These values are written in network byte order.
+Each is used as a transition time (as returned by
+.Xt time 2 )
+at which the rules for computing local time change.
+.It Va tzh_timecnt
+one-byte unsigned integer values;
+each one but the last tells which of the different types of local time types
+described in the file is associated with the time period
+starting with the same-indexed transition time
+and continuing up to but not including the next transition time.
+(The last time type is present only for consistency checking with the
+POSIX-style TZ string described below.)
+These values serve as indices into the next field.
+.It Va tzh_typecnt
+.Vt ttinfo
+entries, each defined as follows:
+.Pp
+.Bd -literal -offset indent
+struct ttinfo {
+	int32_t	tt_utoff;
+	unsigned char	tt_isdst;
+	unsigned char	tt_desigidx;
+};
+.Ed
+.Pp
+Each structure is written as a four-byte signed integer value for
+.Va tt_utoff ,
+in network byte order, followed by a one-byte boolean for
+.Va tt_isdst
+and a one-byte value for
+.Va tt_desigidx .
+In each structure,
+.Va tt_utoff
+gives the number of seconds to be added to UT,
+.Va tt_isdst
+tells whether
+.Va tm_isdst
+should be set by
+.Xr localtime 3
+and
+.Va tt_desigidx
+serves as an index into the array of time zone abbreviation bytes
+that follow the
+.Vt ttinfo
+entries in the file; if the designated string is "\*-00", the
+.Vt ttinfo
+entry is a placeholder indicating that local time is unspecified.
+The
+.Va tt_utoff
+value is never equal to \-2**31, to let 32-bit clients negate it without
+overflow.
+Also, in realistic applications
+.Va tt_utoff
+is in the range [\-89999, 93599] (i.e., more than \-25 hours and less
+than 26 hours); this allows easy support by implementations that
+already support the POSIX-required range [\-24:59:59, 25:59:59].
+.It Va tzh_charcnt
+bytes that represent time zone designations,
+which are null-terminated byte strings, each indexed by the
+.Va tt_desigidx
+values mentioned above.
+The byte strings can overlap if one is a suffix of the other.
+The encoding of these strings is not specified.
+.It Va tzh_leapcnt
+pairs of four-byte values, written in network byte order;
+the first value of each pair gives the nonnegative time
+(as returned by
+.Xr time 3 )
+at which a leap second occurs or at which the leap second table expires;
+the second is a signed integer specifying the correction, which is the
+.Em total
+number of leap seconds to be applied during the time period
+starting at the given time.
+The pairs of values are sorted in strictly ascending order by time.
+Each pair denotes one leap second, either positive or negative,
+except that if the last pair has the same correction as the previous one,
+the last pair denotes the leap second table's expiration time.
+Each leap second is at the end of a UTC calendar month.
+The first leap second has a nonnegative occurrence time,
+and is a positive leap second if and only if its correction is positive;
+the correction for each leap second after the first differs
+from the previous leap second by either 1 for a positive leap second,
+or \-1 for a negative leap second.
+If the leap second table is empty, the leap-second correction is zero
+for all timestamps;
+otherwise, for timestamps before the first occurrence time,
+the leap-second correction is zero if the first pair's correction is 1 or \-1,
+and is unspecified otherwise (which can happen only in files
+truncated at the start).
+.It Va tzh_ttisstdcnt
+standard/wall indicators, each stored as a one-byte boolean;
+they tell whether the transition times associated with local time types
+were specified as standard time or local (wall clock) time.
+.It Va tzh_ttisutcnt
+UT/local indicators, each stored as a one-byte boolean;
+they tell whether the transition times associated with local time types
+were specified as UT or local time.
+If a UT/local indicator is set, the corresponding standard/wall indicator
+must also be set.
+.El
+.Pp
+The standard/wall and UT/local indicators were designed for
+transforming a TZif file's transition times into transitions appropriate
+for another time zone specified via a POSIX-style TZ string that lacks rules.
+For example, when TZ="EET\*-2EEST" and there is no TZif file "EET\*-2EEST",
+the idea was to adapt the transition times from a TZif file with the
+well-known name "posixrules" that is present only for this purpose and
+is a copy of the file "Europe/Brussels", a file with a different UT offset.
+POSIX does not specify this obsolete transformational behavior,
+the default rules are installation-dependent, and no implementation
+is known to support this feature for timestamps past 2037,
+so users desiring (say) Greek time should instead specify
+TZ="Europe/Athens" for better historical coverage, falling back on
+TZ="EET\*-2EEST,M3.5.0/3,M10.5.0/4" if POSIX conformance is required
+and older timestamps need not be handled accurately.
+.Pp
+The
+.Xr localtime 3
+function
+normally uses the first
+.Vt ttinfo
+structure in the file
+if either
+.Va tzh_timecnt
+is zero or the time argument is less than the first transition time recorded
+in the file.
+.Ss Version 2 format
+For version-2-format timezone files,
+the above header and data are followed by a second header and data,
+identical in format except that
+eight bytes are used for each transition time or leap second time.
+(Leap second counts remain four bytes.)
+After the second header and data comes a newline-enclosed,
+POSIX-TZ-environment-variable-style string for use in handling instants
+after the last transition time stored in the file
+or for all instants if the file has no transitions.
+The POSIX-style TZ string is empty (i.e., nothing between the newlines)
+if there is no POSIX-style representation for such instants.
+If nonempty, the POSIX-style TZ string must agree with the local time
+type after the last transition time if present in the eight-byte data;
+for example, given the string
+.Dq "WET0WEST,M3.5.0,M10.5.0/3"
+then if a last transition time is in July, the transition's local time
+type must specify a daylight-saving time abbreviated
+.Dq "WEST"
+that is one hour east of UT.
+Also, if there is at least one transition, time type 0 is associated
+with the time period from the indefinite past up to but not including
+the earliest transition time.
+.Ss Version 3 format
+For version-3-format timezone files, the POSIX-TZ-style string may
+use two minor extensions to the POSIX TZ format, as described in
+.Xr newtzset 3 .
+First, the hours part of its transition times may be signed and range from
+\-167 through 167 instead of the POSIX-required unsigned values
+from 0 through 24.
+Second, DST is in effect all year if it starts
+January 1 at 00:00 and ends December 31 at 24:00 plus the difference
+between daylight saving and standard time.
+.Ss Version 4 format
+For version-4-format TZif files,
+the first leap second record can have a correction that is neither
++1 nor \-1, to represent truncation of the TZif file at the start.
+Also, if two or more leap second transitions are present and the last
+entry's correction equals the previous one, the last entry
+denotes the expiration of the leap second table instead of a leap second;
+timestamps after this expiration are unreliable in that future
+releases will likely add leap second entries after the expiration, and
+the added leap seconds will change how post-expiration timestamps are treated.
+.Ss Interoperability considerations
+Future changes to the format may append more data.
+.Pp
+Version 1 files are considered a legacy format and
+should not be generated, as they do not support transition
+times after the year 2038.
+Readers that understand only Version 1 must ignore
+any data that extends beyond the calculated end of the version
+1 data block.
+.Pp
+Other than version 1, writers should generate
+the lowest version number needed by a file's data.
+For example, a writer should generate a version 4 file
+only if its leap second table either expires or is truncated at the start.
+Likewise, a writer not generating a version 4 file
+should generate a version 3 file only if
+TZ string extensions are necessary to accurately
+model transition times.
+.Pp
+The sequence of time changes defined by the version 1
+header and data block should be a contiguous sub-sequence
+of the time changes defined by the version 2+ header and data
+block, and by the footer.
+This guideline helps obsolescent version 1 readers
+agree with current readers about timestamps within the
+contiguous sub-sequence.
+It also lets writers not
+supporting obsolescent readers use a
+.Va tzh_timecnt
+of zero
+in the version 1 data block to save space.
+.Pp
+When a TZif file contains a leap second table expiration
+time, TZif readers should either refuse to process
+post-expiration timestamps, or process them as if the expiration
+time did not exist (possibly with an error indication).
+.Pp
+Time zone designations should consist of at least three (3)
+and no more than six (6) ASCII characters from the set of
+alphanumerics,
+.Dq "\*-" ,
+and
+.Dq "+" .
+This is for compatibility with POSIX requirements for
+time zone abbreviations.
+.Pp
+When reading a version 2 or higher file, readers
+should ignore the version 1 header and data block except for
+the purpose of skipping over them.
+.Pp
+Readers should calculate the total lengths of the
+headers and data blocks and check that they all fit within
+the actual file size, as part of a validity check for the file.
+.Pp
+When a positive leap second occurs, readers should append an extra
+second to the local minute containing the second just before the leap
+second.
+If this occurs when the UTC offset is not a multiple of 60
+seconds, the leap second occurs earlier than the last second of the
+local minute and the minute's remaining local seconds are numbered
+through 60 instead of the usual 59; the UTC offset is unaffected.
+.Ss Common interoperability issues
+This section documents common problems in reading or writing TZif files.
+Most of these are problems in generating TZif files for use by
+older readers.
+The goals of this section are:
+.Bl -bullet
+.It
+to help TZif writers output files that avoid common
+pitfalls in older or buggy TZif readers,
+.It
+to help TZif readers avoid common pitfalls when reading
+files generated by future TZif writers, and
+.It
+to help any future specification authors see what sort of
+problems arise when the TZif format is changed.
+.El
+.Pp
+When new versions of the TZif format have been defined, a
+design goal has been that a reader can successfully use a TZif
+file even if the file is of a later TZif version than what the
+reader was designed for.
+When complete compatibility was not achieved, an attempt was
+made to limit glitches to rarely used timestamps and allow
+simple partial workarounds in writers designed to generate
+new-version data useful even for older-version readers.
+This section attempts to document these compatibility issues and
+workarounds, as well as to document other common bugs in
+readers.
+.Pp
+Interoperability problems with TZif include the following:
+.Bl -bullet
+.It
+Some readers examine only version 1 data.
+As a partial workaround, a writer can output as much version 1
+data as possible.
+However, a reader should ignore version 1 data, and should use
+version 2+ data even if the reader's native timestamps have only
+32 bits.
+.It
+Some readers designed for version 2 might mishandle
+timestamps after a version 3 or higher file's last transition, because
+they cannot parse extensions to POSIX in the TZ-like string.
+As a partial workaround, a writer can output more transitions
+than necessary, so that only far-future timestamps are
+mishandled by version 2 readers.
+.It
+Some readers designed for version 2 do not support
+permanent daylight saving time with transitions after 24:00
+\(en e.g., a TZ string
+.Dq "EST5EDT,0/0,J365/25"
+denoting permanent Eastern Daylight Time
+(\-04).
+As a workaround, a writer can substitute standard time
+for two time zones east, e.g.,
+.Dq "XXX3EDT4,0/0,J365/23"
+for a time zone with a never-used standard time (XXX, \-03)
+and negative daylight saving time (EDT, \-04) all year.
+Alternatively,
+as a partial workaround a writer can substitute standard time
+for the next time zone east \(en e.g.,
+.Dq "AST4"
+for permanent
+Atlantic Standard Time (\-04).
+.It
+Some readers designed for version 2 or 3, and that require strict
+conformance to RFC 8536, reject version 4 files whose leap second
+tables are truncated at the start or that end in expiration times.
+.It
+Some readers ignore the footer, and instead predict future
+timestamps from the time type of the last transition.
+As a partial workaround, a writer can output more transitions
+than necessary.
+.It
+Some readers do not use time type 0 for timestamps before
+the first transition, in that they infer a time type using a
+heuristic that does not always select time type 0.
+As a partial workaround, a writer can output a dummy (no-op)
+first transition at an early time.
+.It
+Some readers mishandle timestamps before the first
+transition that has a timestamp not less than \-2**31.
+Readers that support only 32-bit timestamps are likely to be
+more prone to this problem, for example, when they process
+64-bit transitions only some of which are representable in 32
+bits.
+As a partial workaround, a writer can output a dummy
+transition at timestamp \-2**31.
+.It
+Some readers mishandle a transition if its timestamp has
+the minimum possible signed 64-bit value.
+Timestamps less than \-2**59 are not recommended.
+.It
+Some readers mishandle POSIX-style TZ strings that
+contain
+.Dq "<"
+or
+.Dq ">".
+As a partial workaround, a writer can avoid using
+.Dq "<"
+or
+.Dq ">"
+for time zone abbreviations containing only alphabetic
+characters.
+.It
+Many readers mishandle time zone abbreviations that contain
+non-ASCII characters.
+These characters are not recommended.
+.It
+Some readers may mishandle time zone abbreviations that
+contain fewer than 3 or more than 6 characters, or that
+contain ASCII characters other than alphanumerics,
+.Dq "\*-",
+and
+.Dq "+".
+These abbreviations are not recommended.
+.It
+Some readers mishandle TZif files that specify
+daylight-saving time UT offsets that are less than the UT
+offsets for the corresponding standard time.
+These readers do not support locations like Ireland, which
+uses the equivalent of the POSIX TZ string
+.Dq "IST\*-1GMT0,M10.5.0,M3.5.0/1" ,
+observing standard time
+(IST, +01) in summer and daylight saving time (GMT, +00) in winter.
+As a partial workaround, a writer can output data for the
+equivalent of the POSIX TZ string
+.Dq "GMT0IST,M3.5.0/1,M10.5.0" ,
+thus swapping standard and daylight saving time.
+Although this workaround misidentifies which part of the year
+uses daylight saving time, it records UT offsets and time zone
+abbreviations correctly.
+.It
+Some readers generate ambiguous timestamps for positive leap seconds
+that occur when the UTC offset is not a multiple of 60 seconds.
+For example, in a timezone with UTC offset +01:23:45 and with
+a positive leap second 78796801 (1972-06-30 23:59:60 UTC), some readers will
+map both 78796800 and 78796801 to 01:23:45 local time the next day
+instead of mapping the latter to 01:23:46, and they will map 78796815 to
+01:23:59 instead of to 01:23:60.
+This has not yet been a practical problem, since no civil authority
+has observed such UTC offsets since leap seconds were
+introduced in 1972.
+.El
+.Pp
+Some interoperability problems are reader bugs that
+are listed here mostly as warnings to developers of readers.
+.Bl -bullet
+.It
+Some readers do not support negative timestamps.
+Developers of distributed applications should keep this
+in mind if they need to deal with pre-1970 data.
+.It
+Some readers mishandle timestamps before the first
+transition that has a nonnegative timestamp.
+Readers that do not support negative timestamps are likely to
+be more prone to this problem.
+.It
+Some readers mishandle time zone abbreviations like
+.Dq "\*-08"
+that contain
+.Dq "+" ,
+.Dq "\*-" ,
+or digits.
+.It
+Some readers mishandle UT offsets that are out of the
+traditional range of \-12 through +12 hours, and so do not
+support locations like Kiritimati that are outside this
+range.
+.It
+Some readers mishandle UT offsets in the range [\-3599, \-1]
+seconds from UT, because they integer-divide the offset by
+3600 to get 0 and then display the hour part as
+.Dq "+00" .
+.It
+Some readers mishandle UT offsets that are not a multiple
+of one hour, or of 15 minutes, or of 1 minute.
+.El
+.Sh SEE ALSO
+.Xr time 3 ,
+.Xr localtime 3 ,
+.Xr tzset 3 ,
+.Xr tzsetup 8 ,
+.Xr zic 8 ,
+.Xr zdump 8
+.Rs
+.%A A. Olson
+.%A P. Eggert
+.%A K. Murchison
+.%T "The Time Zone Information Format (TZif)"
+.%R RFC 8536
+.%D February 2019
+.%U https://datatracker.ietf.org/doc/html/rfc8536
+.%U https://doi.org/10.17487/RFC8536
+.Re
diff --git a/contrib/tzcode/tzfile.h b/contrib/tzcode/tzfile.h
new file mode 100644
index 000000000000..e59d2ea4bb47
--- /dev/null
+++ b/contrib/tzcode/tzfile.h
@@ -0,0 +1,125 @@
+/* Layout and location of TZif files.  */
+
+#ifndef TZFILE_H
+#define TZFILE_H
+
+
+/*
+** This file is in the public domain, so clarified as of
+** 1996-06-05 by Arthur David Olson.
+**
+** $FreeBSD$
+*/
+
+/*
+** This header is for use ONLY with the time conversion code.
+** There is no guarantee that it will remain unchanged,
+** or that it will remain at all.
+** Do NOT copy it to any system include directory.
+** Thank you!
+*/
+
+/*
+** Information about time zone files.
+*/
+
+#ifndef TZDIR
+# define TZDIR "/usr/share/zoneinfo" /* Time zone object file directory */
+#endif /* !defined TZDIR */
+
+#ifndef TZDEFAULT
+# define TZDEFAULT "/etc/localtime"
+#endif /* !defined TZDEFAULT */
+
+#ifndef TZDEFRULES
+# define TZDEFRULES "posixrules"
+#endif /* !defined TZDEFRULES */
+
+
+/* See Internet RFC 8536 for more details about the following format.  */
+
+/*
+** Each file begins with. . .
+*/
+
+#define	TZ_MAGIC	"TZif"
+
+struct tzhead {
+	char	tzh_magic[4];		/* TZ_MAGIC */
+	char	tzh_version[1];		/* '\0' or '2'-'4' as of 2021 */
+	char	tzh_reserved[15];	/* reserved; must be zero */
+	char	tzh_ttisutcnt[4];	/* coded number of trans. time flags */
+	char	tzh_ttisstdcnt[4];	/* coded number of trans. time flags */
+	char	tzh_leapcnt[4];		/* coded number of leap seconds */
+	char	tzh_timecnt[4];		/* coded number of transition times */
+	char	tzh_typecnt[4];		/* coded number of local time types */
+	char	tzh_charcnt[4];		/* coded number of abbr. chars */
+};
+
+/*
+** . . .followed by. . .
+**
+**	tzh_timecnt (char [4])s		coded transition times a la time(2)
+**	tzh_timecnt (unsigned char)s	types of local time starting at above
+**	tzh_typecnt repetitions of
+**		one (char [4])		coded UT offset in seconds
+**		one (unsigned char)	used to set tm_isdst
+**		one (unsigned char)	that's an abbreviation list index
+**	tzh_charcnt (char)s		'\0'-terminated zone abbreviations
+**	tzh_leapcnt repetitions of
+**		one (char [4])		coded leap second transition times
+**		one (char [4])		total correction after above
+**	tzh_ttisstdcnt (char)s		indexed by type; if 1, transition
+**					time is standard time, if 0,
+**					transition time is local (wall clock)
+**					time; if absent, transition times are
+**					assumed to be local time
+**	tzh_ttisutcnt (char)s		indexed by type; if 1, transition
+**					time is UT, if 0, transition time is
+**					local time; if absent, transition
+**					times are assumed to be local time.
+**					When this is 1, the corresponding
+**					std/wall indicator must also be 1.
+*/
+
+/*
+** If tzh_version is '2' or greater, the above is followed by a second instance
+** of tzhead and a second instance of the data in which each coded transition
+** time uses 8 rather than 4 chars,
+** then a POSIX-TZ-environment-variable-style string for use in handling
+** instants after the last transition time stored in the file
+** (with nothing between the newlines if there is no POSIX representation for
+** such instants).
+**
+** If tz_version is '3' or greater, the above is extended as follows.
+** First, the POSIX TZ string's hour offset may range from -167
+** through 167 as compared to the POSIX-required 0 through 24.
+** Second, its DST start time may be January 1 at 00:00 and its stop
+** time December 31 at 24:00 plus the difference between DST and
+** standard time, indicating DST all year.
+*/
+
+/*
+** In the current implementation, "tzset()" refuses to deal with files that
+** exceed any of the limits below.
+*/
+
+#ifndef TZ_MAX_TIMES
+# define TZ_MAX_TIMES 2000
+#endif /* !defined TZ_MAX_TIMES */
+
+#ifndef TZ_MAX_TYPES
+/* This must be at least 17 for Europe/Samara and Europe/Vilnius.  */
+# define TZ_MAX_TYPES 256 /* Limited by what (unsigned char)'s can hold */
+#endif /* !defined TZ_MAX_TYPES */
+
+#ifndef TZ_MAX_CHARS
+# define TZ_MAX_CHARS 50	/* Maximum number of abbreviation characters */
+				/* (limited by what unsigned chars can hold) */
+#endif /* !defined TZ_MAX_CHARS */
+
+#ifndef TZ_MAX_LEAPS
+# define TZ_MAX_LEAPS 50	/* Maximum number of leap second corrections */
+#endif /* !defined TZ_MAX_LEAPS */
+
+#endif /* !defined TZFILE_H */
diff --git a/contrib/tzcode/tzselect.8 b/contrib/tzcode/tzselect.8
new file mode 100644
index 000000000000..846b867be1c0
--- /dev/null
+++ b/contrib/tzcode/tzselect.8
@@ -0,0 +1,125 @@
+.\" This file is in the public domain, so clarified as of
+.\" 2009-05-17 by Arthur David Olson.
+.TH TZSELECT 8
+.SH NAME
+tzselect \- select a timezone
+.SH SYNOPSIS
+.ie \n(.g .ds - \f(CR-\fP
+.el .ds - \-
+.ds d " degrees
+.ds m " minutes
+.ds s " seconds
+.ds _ " \&
+.if t \{\
+. if \n(.g .if c \(de .if c \(fm .if c \(sd \{\
+.  ds d \(de
+.  ds m \(fm
+.  ds s \(sd
+.  ds _ \|
+. \}
+.\}
+.B tzselect
+[
+.B \*-c
+.I coord
+] [
+.B \*-n
+.I limit
+] [
+.B \*-\*-help
+] [
+.B \*-\*-version
+]
+.SH DESCRIPTION
+The
+.B tzselect
+program asks the user for information about the current location,
+and outputs the resulting timezone to standard output.
+The output is suitable as a value for the TZ environment variable.
+.PP
+All interaction with the user is done via standard input and standard error.
+.SH OPTIONS
+.TP
+.BI "\*-c " coord
+Instead of asking for continent and then country and then city,
+ask for selection from time zones whose largest cities
+are closest to the location with geographical coordinates
+.I coord.
+Use ISO 6709 notation for
+.I coord,
+that is, a latitude immediately followed by a longitude.  The latitude
+and longitude should be signed integers followed by an optional
+decimal point and fraction: positive numbers represent north and east,
+negative south and west.  Latitudes with two and longitudes with three
+integer digits are treated as degrees; latitudes with four or six and
+longitudes with five or seven integer digits are treated as
+.I "DDMM, DDDMM, DDMMSS,"
+or
+.I DDDMMSS
+representing
+.I DD
+or
+.I DDD
+degrees,
+.I MM
+minutes,
+and zero or
+.I SS
+seconds, with any trailing fractions represent fractional minutes or
+(if
+.I SS
+is present) seconds.  The decimal point is that of the current locale.
+For example, in the (default) C locale,
+.B "\*-c\ +40.689\*-074.045"
+specifies 40.689\*d\*_N, 74.045\*d\*_W,
+.B "\*-c\ +4041.4\*-07402.7"
+specifies 40\*d\*_41.4\*m\*_N, 74\*d\*_2.7\*m\*_W, and
+.B "\*-c\ +404121\*-0740240"
+specifies 40\*d\*_41\*m\*_21\*s\*_N, 74\*d\*_2\*m\*_40\*s\*_W.
+If
+.I coord
+is not one of the documented forms, the resulting behavior is unspecified.
+.TP
+.BI "\*-n " limit
+When
+.B \*-c
+is used, display the closest
+.I limit
+locations (default 10).
+.TP
+.B "\*-\*-help"
+Output help information and exit.
+.TP
+.B "\*-\*-version"
+Output version information and exit.
+.SH "ENVIRONMENT VARIABLES"
+.TP
+\f3AWK\fP
+Name of a Posix-compliant
+.B awk
+program (default:
+.BR awk ).
+.TP
+\f3TZDIR\fP
+Name of the directory containing timezone data files (default:
+.BR /usr/share/zoneinfo ).
+.SH FILES
+.TP
+\f2TZDIR\fP\f3/iso3166.tab\fP
+Table of ISO 3166 2-letter country codes and country names.
+.TP
+\f2TZDIR\fP\f3/zone1970.tab\fP
+Table of country codes, latitude and longitude, timezones, and
+descriptive comments.
+.TP
+\f2TZDIR\fP\f3/\fP\f2TZ\fP
+Timezone data file for timezone \f2TZ\fP.
+.SH "EXIT STATUS"
+The exit status is zero if a timezone was successfully obtained from the user,
+nonzero otherwise.
+.SH "SEE ALSO"
+newctime(3), tzfile(5), zdump(8), zic(8)
+.SH NOTES
+Applications should not assume that
+.BR tzselect 's
+output matches the user's political preferences.
diff --git a/contrib/tzcode/tzselect.ksh b/contrib/tzcode/tzselect.ksh
new file mode 100644
index 000000000000..28c32a2430f8
--- /dev/null
+++ b/contrib/tzcode/tzselect.ksh
@@ -0,0 +1,586 @@
+#!/bin/bash
+# Ask the user about the time zone, and output the resulting TZ value to stdout.
+# Interact with the user via stderr and stdin.
+
+PKGVERSION='(tzcode) '
+TZVERSION=see_Makefile
+REPORT_BUGS_TO=tz@iana.org
+
+# Contributed by Paul Eggert.  This file is in the public domain.
+
+# Porting notes:
+#
+# This script requires a Posix-like shell and prefers the extension of a
+# 'select' statement.  The 'select' statement was introduced in the
+# Korn shell and is available in Bash and other shell implementations.
+# If your host lacks both Bash and the Korn shell, you can get their
+# source from one of these locations:
+#
+#	Bash <https://www.gnu.org/software/bash/>
+#	Korn Shell <http://www.kornshell.com/>
+#	MirBSD Korn Shell <http://www.mirbsd.org/mksh.htm>
+#
+# For portability to Solaris 10 /bin/sh (supported by Oracle through
+# January 2024) this script avoids some POSIX features and common
+# extensions, such as $(...) (which works sometimes but not others),
+# $((...)), ! CMD, ${#ID}, ${ID##PAT}, ${ID%%PAT}, and $10.
+
+#
+# This script also uses several features of modern awk programs.
+# If your host lacks awk, or has an old awk that does not conform to Posix,
+# you can use either of the following free programs instead:
+#
+#	Gawk (GNU awk) <https://www.gnu.org/software/gawk/>
+#	mawk <https://invisible-island.net/mawk/>
+#	nawk <https://github.com/onetrueawk/awk>
+
+
+# Specify default values for environment variables if they are unset.
+: ${AWK=awk}
+: ${TZDIR=`pwd`}
+
+# Output one argument as-is to standard output.
+# Safer than 'echo', which can mishandle '\' or leading '-'.
+say() {
+    printf '%s\n' "$1"
+}
+
+# Check for awk Posix compliance.
+($AWK -v x=y 'BEGIN { exit 123 }') </dev/null >/dev/null 2>&1
+[ $? = 123 ] || {
+	say >&2 "$0: Sorry, your '$AWK' program is not Posix compatible."
+	exit 1
+}
+
+coord=
+location_limit=10
+zonetabtype=zone1970
+
+usage="Usage: tzselect [--version] [--help] [-c COORD] [-n LIMIT]
+Select a timezone interactively.
+
+Options:
+
+  -c COORD
+    Instead of asking for continent and then country and then city,
+    ask for selection from time zones whose largest cities
+    are closest to the location with geographical coordinates COORD.
+    COORD should use ISO 6709 notation, for example, '-c +4852+00220'
+    for Paris (in degrees and minutes, North and East), or
+    '-c -35-058' for Buenos Aires (in degrees, South and West).
+
+  -n LIMIT
+    Display at most LIMIT locations when -c is used (default $location_limit).
+
+  --version
+    Output version information.
+
+  --help
+    Output this help.
+
+Report bugs to $REPORT_BUGS_TO."
+
+# Ask the user to select from the function's arguments,
+# and assign the selected argument to the variable 'select_result'.
+# Exit on EOF or I/O error.  Use the shell's 'select' builtin if available,
+# falling back on a less-nice but portable substitute otherwise.
+if
+  case $BASH_VERSION in
+  ?*) : ;;
+  '')
+    # '; exit' should be redundant, but Dash doesn't properly fail without it.
+    (eval 'set --; select x; do break; done; exit') </dev/null 2>/dev/null
+  esac
+then
+  # Do this inside 'eval', as otherwise the shell might exit when parsing it
+  # even though it is never executed.
+  eval '
+    doselect() {
+      select select_result
+      do
+	case $select_result in
+	"") echo >&2 "Please enter a number in range." ;;
+	?*) break
+	esac
+      done || exit
+    }
+  '
+else
+  doselect() {
+    # Field width of the prompt numbers.
+    select_width=`expr $# : '.*'`
+
+    select_i=
+
+    while :
+    do
+      case $select_i in
+      '')
+	select_i=0
+	for select_word
+	do
+	  select_i=`expr $select_i + 1`
+	  printf >&2 "%${select_width}d) %s\\n" $select_i "$select_word"
+	done ;;
+      *[!0-9]*)
+	echo >&2 'Please enter a number in range.' ;;
+      *)
+	if test 1 -le $select_i && test $select_i -le $#; then
+	  shift `expr $select_i - 1`
+	  select_result=$1
+	  break
+	fi
+	echo >&2 'Please enter a number in range.'
+      esac
+
+      # Prompt and read input.
+      printf >&2 %s "${PS3-#? }"
+      read select_i || exit
+    done
+  }
+fi
+
+while getopts c:n:t:-: opt
+do
+    case $opt$OPTARG in
+    c*)
+	coord=$OPTARG ;;
+    n*)
+	location_limit=$OPTARG ;;
+    t*) # Undocumented option, used for developer testing.
+	zonetabtype=$OPTARG ;;
+    -help)
+	exec echo "$usage" ;;
+    -version)
+	exec echo "tzselect $PKGVERSION$TZVERSION" ;;
+    -*)
+	say >&2 "$0: -$opt$OPTARG: unknown option; try '$0 --help'"; exit 1 ;;
+    *)
+	say >&2 "$0: try '$0 --help'"; exit 1 ;;
+    esac
+done
+
+shift `expr $OPTIND - 1`
+case $# in
+0) ;;
+*) say >&2 "$0: $1: unknown argument"; exit 1 ;;
+esac
+
+# Make sure the tables are readable.
+TZ_COUNTRY_TABLE=$TZDIR/iso3166.tab
+TZ_ZONE_TABLE=$TZDIR/$zonetabtype.tab
+for f in $TZ_COUNTRY_TABLE $TZ_ZONE_TABLE
+do
+	<"$f" || {
+		say >&2 "$0: time zone files are not set up correctly"
+		exit 1
+	}
+done
+
+# If the current locale does not support UTF-8, convert data to current
+# locale's format if possible, as the shell aligns columns better that way.
+# Check the UTF-8 of U+12345 CUNEIFORM SIGN URU TIMES KI.
+$AWK 'BEGIN { u12345 = "\360\222\215\205"; exit length(u12345) != 1 }' || {
+    { tmp=`(mktemp -d) 2>/dev/null` || {
+	tmp=${TMPDIR-/tmp}/tzselect.$$ &&
+	(umask 77 && mkdir -- "$tmp")
+    };} &&
+    trap 'status=$?; rm -fr -- "$tmp"; exit $status' 0 HUP INT PIPE TERM &&
+    (iconv -f UTF-8 -t //TRANSLIT <"$TZ_COUNTRY_TABLE" >$tmp/iso3166.tab) \
+        2>/dev/null &&
+    TZ_COUNTRY_TABLE=$tmp/iso3166.tab &&
+    iconv -f UTF-8 -t //TRANSLIT <"$TZ_ZONE_TABLE" >$tmp/$zonetabtype.tab &&
+    TZ_ZONE_TABLE=$tmp/$zonetabtype.tab
+}
+
+newline='
+'
+IFS=$newline
+
+
+# Awk script to read a time zone table and output the same table,
+# with each column preceded by its distance from 'here'.
+output_distances='
+  BEGIN {
+    FS = "\t"
+    while (getline <TZ_COUNTRY_TABLE)
+      if ($0 ~ /^[^#]/)
+        country[$1] = $2
+    country["US"] = "US" # Otherwise the strings get too long.
+  }
+  function abs(x) {
+    return x < 0 ? -x : x;
+  }
+  function min(x, y) {
+    return x < y ? x : y;
+  }
+  function convert_coord(coord, deg, minute, ilen, sign, sec) {
+    if (coord ~ /^[-+]?[0-9]?[0-9][0-9][0-9][0-9][0-9][0-9]([^0-9]|$)/) {
+      degminsec = coord
+      intdeg = degminsec < 0 ? -int(-degminsec / 10000) : int(degminsec / 10000)
+      minsec = degminsec - intdeg * 10000
+      intmin = minsec < 0 ? -int(-minsec / 100) : int(minsec / 100)
+      sec = minsec - intmin * 100
+      deg = (intdeg * 3600 + intmin * 60 + sec) / 3600
+    } else if (coord ~ /^[-+]?[0-9]?[0-9][0-9][0-9][0-9]([^0-9]|$)/) {
+      degmin = coord
+      intdeg = degmin < 0 ? -int(-degmin / 100) : int(degmin / 100)
+      minute = degmin - intdeg * 100
+      deg = (intdeg * 60 + minute) / 60
+    } else
+      deg = coord
+    return deg * 0.017453292519943296
+  }
+  function convert_latitude(coord) {
+    match(coord, /..*[-+]/)
+    return convert_coord(substr(coord, 1, RLENGTH - 1))
+  }
+  function convert_longitude(coord) {
+    match(coord, /..*[-+]/)
+    return convert_coord(substr(coord, RLENGTH))
+  }
+  # Great-circle distance between points with given latitude and longitude.
+  # Inputs and output are in radians.  This uses the great-circle special
+  # case of the Vicenty formula for distances on ellipsoids.
+  function gcdist(lat1, long1, lat2, long2, dlong, x, y, num, denom) {
+    dlong = long2 - long1
+    x = cos(lat2) * sin(dlong)
+    y = cos(lat1) * sin(lat2) - sin(lat1) * cos(lat2) * cos(dlong)
+    num = sqrt(x * x + y * y)
+    denom = sin(lat1) * sin(lat2) + cos(lat1) * cos(lat2) * cos(dlong)
+    return atan2(num, denom)
+  }
+  # Parallel distance between points with given latitude and longitude.
+  # This is the product of the longitude difference and the cosine
+  # of the latitude of the point that is further from the equator.
+  # I.e., it considers longitudes to be further apart if they are
+  # nearer the equator.
+  function pardist(lat1, long1, lat2, long2) {
+    return abs(long1 - long2) * min(cos(lat1), cos(lat2))
+  }
+  # The distance function is the sum of the great-circle distance and
+  # the parallel distance.  It could be weighted.
+  function dist(lat1, long1, lat2, long2) {
+    return gcdist(lat1, long1, lat2, long2) + pardist(lat1, long1, lat2, long2)
+  }
+  BEGIN {
+    coord_lat = convert_latitude(coord)
+    coord_long = convert_longitude(coord)
+  }
+  /^[^#]/ {
+    here_lat = convert_latitude($2)
+    here_long = convert_longitude($2)
+    line = $1 "\t" $2 "\t" $3
+    sep = "\t"
+    ncc = split($1, cc, /,/)
+    for (i = 1; i <= ncc; i++) {
+      line = line sep country[cc[i]]
+      sep = ", "
+    }
+    if (NF == 4)
+      line = line " - " $4
+    printf "%g\t%s\n", dist(coord_lat, coord_long, here_lat, here_long), line
+  }
+'
+
+# Begin the main loop.  We come back here if the user wants to retry.
+while
+
+	echo >&2 'Please identify a location' \
+		'so that time zone rules can be set correctly.'
+
+	continent=
+	country=
+	region=
+
+	case $coord in
+	?*)
+		continent=coord;;
+	'')
+
+	# Ask the user for continent or ocean.
+
+	echo >&2 'Please select a continent, ocean, "coord", or "TZ".'
+
+        quoted_continents=`
+	  $AWK '
+	    function handle_entry(entry) {
+	      entry = substr(entry, 1, index(entry, "/") - 1)
+	      if (entry == "America")
+	       entry = entry "s"
+	      if (entry ~ /^(Arctic|Atlantic|Indian|Pacific)$/)
+	       entry = entry " Ocean"
+	      printf "'\''%s'\''\n", entry
+	    }
+	    BEGIN { FS = "\t" }
+	    /^[^#]/ {
+              handle_entry($3)
+            }
+	    /^#@/ {
+	      ncont = split($2, cont, /,/)
+	      for (ci = 1; ci <= ncont; ci++) {
+	        handle_entry(cont[ci])
+	      }
+	    }
+          ' <"$TZ_ZONE_TABLE" |
+	  sort -u |
+	  tr '\n' ' '
+	  echo ''
+	`
+
+	eval '
+	    doselect '"$quoted_continents"' \
+		"coord - I want to use geographical coordinates." \
+		"TZ - I want to specify the timezone using the Posix TZ format."
+	    continent=$select_result
+	    case $continent in
+	    Americas) continent=America;;
+	    *" "*) continent=`expr "$continent" : '\''\([^ ]*\)'\''`
+	    esac
+	'
+	esac
+
+	case $continent in
+	TZ)
+		# Ask the user for a Posix TZ string.  Check that it conforms.
+		while
+			echo >&2 'Please enter the desired value' \
+				'of the TZ environment variable.'
+			echo >&2 'For example, AEST-10 is abbreviated' \
+				'AEST and is 10 hours'
+			echo >&2 'ahead (east) of Greenwich,' \
+				'with no daylight saving time.'
+			read TZ
+			$AWK -v TZ="$TZ" 'BEGIN {
+				tzname = "(<[[:alnum:]+-]{3,}>|[[:alpha:]]{3,})"
+				time = "(2[0-4]|[0-1]?[0-9])" \
+				  "(:[0-5][0-9](:[0-5][0-9])?)?"
+				offset = "[-+]?" time
+				mdate = "M([1-9]|1[0-2])\\.[1-5]\\.[0-6]"
+				jdate = "((J[1-9]|[0-9]|J?[1-9][0-9]" \
+				  "|J?[1-2][0-9][0-9])|J?3[0-5][0-9]|J?36[0-5])"
+				datetime = ",(" mdate "|" jdate ")(/" time ")?"
+				tzpattern = "^(:.*|" tzname offset "(" tzname \
+				  "(" offset ")?(" datetime datetime ")?)?)$"
+				if (TZ ~ tzpattern) exit 1
+				exit 0
+			}'
+		do
+		    say >&2 "'$TZ' is not a conforming Posix timezone string."
+		done
+		TZ_for_date=$TZ;;
+	*)
+		case $continent in
+		coord)
+		    case $coord in
+		    '')
+			echo >&2 'Please enter coordinates' \
+				'in ISO 6709 notation.'
+			echo >&2 'For example, +4042-07403 stands for'
+			echo >&2 '40 degrees 42 minutes north,' \
+				'74 degrees 3 minutes west.'
+			read coord;;
+		    esac
+		    distance_table=`$AWK \
+			    -v coord="$coord" \
+			    -v TZ_COUNTRY_TABLE="$TZ_COUNTRY_TABLE" \
+			    "$output_distances" <"$TZ_ZONE_TABLE" |
+		      sort -n |
+		      sed "${location_limit}q"
+		    `
+		    regions=`say "$distance_table" | $AWK '
+		      BEGIN { FS = "\t" }
+		      { print $NF }
+		    '`
+		    echo >&2 'Please select one of the following timezones,' \
+		    echo >&2 'listed roughly in increasing order' \
+			    "of distance from $coord".
+		    doselect $regions
+		    region=$select_result
+		    TZ=`say "$distance_table" | $AWK -v region="$region" '
+		      BEGIN { FS="\t" }
+		      $NF == region { print $4 }
+		    '`
+		    ;;
+		*)
+		# Get list of names of countries in the continent or ocean.
+		countries=`$AWK \
+			-v continent_re="^$continent/" \
+			-v TZ_COUNTRY_TABLE="$TZ_COUNTRY_TABLE" \
+		'
+			BEGIN { FS = "\t" }
+			/^#$/ { next }
+			/^#[^@]/ { next }
+			{
+			  commentary = $0 ~ /^#@/
+			  if (commentary) {
+			    col1ccs = substr($1, 3)
+			    conts = $2
+			  } else {
+			    col1ccs = $1
+			    conts = $3
+			  }
+			  ncc = split(col1ccs, cc, /,/)
+			  ncont = split(conts, cont, /,/)
+			  for (i = 1; i <= ncc; i++) {
+			    elsewhere = commentary
+			    for (ci = 1; ci <= ncont; ci++) {
+			      if (cont[ci] ~ continent_re) {
+				if (!cc_seen[cc[i]]++) cc_list[++ccs] = cc[i]
+				elsewhere = 0
+			      }
+			    }
+			    if (elsewhere) {
+			      for (i = 1; i <= ncc; i++) {
+			        cc_elsewhere[cc[i]] = 1
+			      }
+			    }
+			  }
+			}
+			END {
+				while (getline <TZ_COUNTRY_TABLE) {
+					if ($0 !~ /^#/) cc_name[$1] = $2
+				}
+				for (i = 1; i <= ccs; i++) {
+					country = cc_list[i]
+					if (cc_elsewhere[country]) continue
+					if (cc_name[country]) {
+					  country = cc_name[country]
+					}
+					print country
+				}
+			}
+		' <"$TZ_ZONE_TABLE" | sort -f`
+
+
+		# If there's more than one country, ask the user which one.
+		case $countries in
+		*"$newline"*)
+			echo >&2 'Please select a country' \
+				'whose clocks agree with yours.'
+			doselect $countries
+			country=$select_result;;
+		*)
+			country=$countries
+		esac
+
+
+		# Get list of timezones in the country.
+		regions=`$AWK \
+			-v country="$country" \
+			-v TZ_COUNTRY_TABLE="$TZ_COUNTRY_TABLE" \
+		'
+			BEGIN {
+				FS = "\t"
+				cc = country
+				while (getline <TZ_COUNTRY_TABLE) {
+					if ($0 !~ /^#/  &&  country == $2) {
+						cc = $1
+						break
+					}
+				}
+			}
+			/^#/ { next }
+			$1 ~ cc { print $4 }
+		' <"$TZ_ZONE_TABLE"`
+
+
+		# If there's more than one region, ask the user which one.
+		case $regions in
+		*"$newline"*)
+			echo >&2 'Please select one of the following timezones.'
+			doselect $regions
+			region=$select_result;;
+		*)
+			region=$regions
+		esac
+
+		# Determine TZ from country and region.
+		TZ=`$AWK \
+			-v country="$country" \
+			-v region="$region" \
+			-v TZ_COUNTRY_TABLE="$TZ_COUNTRY_TABLE" \
+		'
+			BEGIN {
+				FS = "\t"
+				cc = country
+				while (getline <TZ_COUNTRY_TABLE) {
+					if ($0 !~ /^#/  &&  country == $2) {
+						cc = $1
+						break
+					}
+				}
+			}
+			/^#/ { next }
+			$1 ~ cc && $4 == region { print $3 }
+		' <"$TZ_ZONE_TABLE"`
+		esac
+
+		# Make sure the corresponding zoneinfo file exists.
+		TZ_for_date=$TZDIR/$TZ
+		<"$TZ_for_date" || {
+			say >&2 "$0: time zone files are not set up correctly"
+			exit 1
+		}
+	esac
+
+
+	# Use the proposed TZ to output the current date relative to UTC.
+	# Loop until they agree in seconds.
+	# Give up after 8 unsuccessful tries.
+
+	extra_info=
+	for i in 1 2 3 4 5 6 7 8
+	do
+		TZdate=`LANG=C TZ="$TZ_for_date" date`
+		UTdate=`LANG=C TZ=UTC0 date`
+		TZsec=`expr "$TZdate" : '.*:\([0-5][0-9]\)'`
+		UTsec=`expr "$UTdate" : '.*:\([0-5][0-9]\)'`
+		case $TZsec in
+		$UTsec)
+			extra_info="
+Selected time is now:	$TZdate.
+Universal Time is now:	$UTdate."
+			break
+		esac
+	done
+
+
+	# Output TZ info and ask the user to confirm.
+
+	echo >&2 ""
+	echo >&2 "The following information has been given:"
+	echo >&2 ""
+	case $country%$region%$coord in
+	?*%?*%)	say >&2 "	$country$newline	$region";;
+	?*%%)	say >&2 "	$country";;
+	%?*%?*) say >&2 "	coord $coord$newline	$region";;
+	%%?*)	say >&2 "	coord $coord";;
+	*)	say >&2 "	TZ='$TZ'"
+	esac
+	say >&2 ""
+	say >&2 "Therefore TZ='$TZ' will be used.$extra_info"
+	say >&2 "Is the above information OK?"
+
+	doselect Yes No
+	ok=$select_result
+	case $ok in
+	Yes) break
+	esac
+do coord=
+done
+
+case $SHELL in
+*csh) file=.login line="setenv TZ '$TZ'";;
+*) file=.profile line="TZ='$TZ'; export TZ"
+esac
+
+test -t 1 && say >&2 "
+You can make this change permanent for yourself by appending the line
+	$line
+to the file '$file' in your home directory; then log out and log in again.
+
+Here is that TZ value again, this time on standard output so that you
+can use the $0 command in shell scripts:"
+
+say "$TZ"
diff --git a/contrib/tzcode/version b/contrib/tzcode/version
new file mode 100644
index 000000000000..b74fa117a223
--- /dev/null
+++ b/contrib/tzcode/version
@@ -0,0 +1 @@
+2022g
diff --git a/contrib/tzcode/version.h b/contrib/tzcode/version.h
new file mode 100644
index 000000000000..12997b874b5e
--- /dev/null
+++ b/contrib/tzcode/version.h
@@ -0,0 +1,3 @@
+static char const PKGVERSION[]="(tzcode) ";
+static char const TZVERSION[]="2022g";
+static char const REPORT_BUGS_TO[]="tz@iana.org";
diff --git a/contrib/tzcode/workman.sh b/contrib/tzcode/workman.sh
new file mode 100644
index 000000000000..6e2da3a80c8d
--- /dev/null
+++ b/contrib/tzcode/workman.sh
@@ -0,0 +1,41 @@
+#! /bin/sh
+# Convert manual page troff stdin to formatted .txt stdout.
+
+# This file is in the public domain, so clarified as of
+# 2009-05-17 by Arthur David Olson.
+
+if (type nroff && type perl) >/dev/null 2>&1; then
+
+  # Tell groff not to emit SGR escape sequences (ANSI color escapes).
+  GROFF_NO_SGR=1
+  export GROFF_NO_SGR
+
+  echo ".am TH
+.hy 0
+.na
+..
+.rm }H
+.rm }F" | nroff -man - ${1+"$@"} | perl -ne '
+	binmode STDIN, '\'':encoding(utf8)'\'';
+	binmode STDOUT, '\'':encoding(utf8)'\'';
+	chomp;
+	s/.\010//g;
+	s/\s*$//;
+	if (/^$/) {
+		$sawblank = 1;
+		next;
+	} else {
+		if ($sawblank && $didprint) {
+			print "\n";
+			$sawblank = 0;
+		}
+		print "$_\n";
+		$didprint = 1;
+	}
+  '
+elif (type mandoc && type col) >/dev/null 2>&1; then
+  mandoc -man -T ascii "$@" | col -bx
+else
+  echo >&2 "$0: please install nroff and perl, or mandoc and col"
+  exit 1
+fi
diff --git a/contrib/tzcode/zdump.8 b/contrib/tzcode/zdump.8
new file mode 100644
index 000000000000..0b9e956526cc
--- /dev/null
+++ b/contrib/tzcode/zdump.8
@@ -0,0 +1,231 @@
+.\" This file is in the public domain, so clarified as of
+.\" 2009-05-17 by Arthur David Olson.
+.\"
+.\" $FreeBSD$
+.\"
+.Dd December 15, 2022
+.Dt ZDUMP 8
+.Os
+.Sh NAME
+.Nm zdump
+.Nd timezone dumper
+.Sh SYNOPSIS
+.Nm
+.Op Fl -help
+.Op Fl -version
+.Op Fl ivV
+.Oo
+.Fl c
+.Op Ar loyear , Ns
+.Ar hiyear
+.Oc
+.Oo
+.Fl t
+.Op Ar lotime , Ns
+.Ar hitime
+.Oc
+.Op Ar timezone ...
+.Sh DESCRIPTION
+The
+.Nm
+program prints the current time in each
+.Ar timezone
+named on the command line.
+.Pp
+The following options are available:
+.Bl -tag -width indent
+.It Fl -version
+Output version information and exit.
+.It Fl -help
+Output short usage message and exit.
+.It Fl i
+Output a description of time intervals.
+For each
+.Ar timezone
+on the command line, output an interval-format description of the
+timezone.
+See
+.Sx "INTERVAL FORMAT"
+below.
+.It Fl v
+Output a verbose description of time intervals.
+For each
+.Ar timezone
+on the command line,
+print the times at the two extreme time values,
+the times (if present) at and just beyond the boundaries of years that
+.Xr localtime 3
+and
+.Xr gmtime 3
+can represent, and
+the times both one second before and exactly at
+each detected time discontinuity.
+Each line is followed by
+.Cm isdst= Ns Ar D
+where
+.Ar D
+is positive, zero, or negative depending on whether
+the given time is daylight saving time, standard time,
+or an unknown time type, respectively.
+Each line is also followed by
+.Cm gmtoff= Ns Ar N
+if the given local time is known to be
+.Ar N
+seconds east of Greenwich.
+.It Fl V
+Like
+.Fl v ,
+except omit output concerning extreme time and year values.
+This generates output that is easier to compare to that of
+implementations with different time representations.
+.It Fl c Oo Ar loyear , Oc Ns Ar hiyear
+Cut off interval output at the given year(s).
+Cutoff times are computed using the proleptic Gregorian calendar with year 0
+and with Universal Time (UT) ignoring leap seconds.
+Cutoffs are at the start of each year, where the lower-bound
+timestamp is inclusive and the upper is exclusive; for example,
+.Ql "-c 1970,2070"
+selects transitions on or after 1970-01-01 00:00:00 UTC
+and before 2070-01-01 00:00:00 UTC.
+The default cutoff is
+.Ql -500,2500 .
+.It Fl t Oo Ar lotime , Oc Ns Ar hitime
+Cut off interval output at the given time(s),
+given in decimal seconds since 1970-01-01 00:00:00
+Coordinated Universal Time (UTC).
+The
+.Ar timezone
+determines whether the count includes leap seconds.
+As with
+.Fl c ,
+the cutoff's lower bound is inclusive and its upper bound is exclusive.
+.El
+.Sh "INTERVAL FORMAT"
+The interval format is a compact text representation that is intended
+to be both human- and machine-readable.
+It consists of an empty line,
+then a line
+.Dq "TZ=\fIstring\fP"
+where
+.Ar string
+is a double-quoted string giving the timezone, a second line
+.Dq "\*- \*- \fIinterval\fP"
+describing the time interval before the first transition if any, and
+zero or more following lines
+.Dq "\fIdate time interval\fP",
+one line for each transition time and following interval.
+Fields are
+separated by single tabs.
+.Pp
+Dates are in
+.Ql "yyyy - mm - dd"
+format and times are in 24-hour
+.Ql "hh : mm : ss"
+format where
+.Ql "hh <24" .
+Times are in local time immediately after the transition.
+A
+time interval description consists of a UT offset in signed
+.Ql "\(+- hhmmss"
+format, a time zone abbreviation, and an isdst flag.
+An abbreviation
+that equals the UT offset is omitted; other abbreviations are
+double-quoted strings unless they consist of one or more alphabetic
+characters.
+An isdst flag is omitted for standard time, and otherwise
+is a decimal integer that is unsigned and positive (typically 1) for
+daylight saving time and negative for unknown.
+.Pp
+In times and in UT offsets with absolute value less than 100 hours,
+the seconds are omitted if they are zero, and
+the minutes are also omitted if they are also zero.
+Positive UT
+offsets are east of Greenwich.
+The UT offset \*-00 denotes a UT
+placeholder in areas where the actual offset is unspecified; by
+convention, this occurs when the UT offset is zero and the time zone
+abbreviation begins with
+.Dq "-"
+or is
+.Dq "zzz".
+.Pp
+In double-quoted strings, escape sequences represent unusual
+characters.
+The escape sequences are \es for space, and \e", \e\e,
+\ef, \en, \er, \et, and \ev with their usual meaning in the C
+programming language.
+E.g., the double-quoted string
+\*(lq"CET\es\e"\e\e"\*(rq represents the character sequence \*(lqCET
+"\e\*(rq.\""
+.Pp
+Here is an example of the output, with the leading empty line omitted.
+(This example is shown with tab stops set far enough apart so that the
+tabbed columns line up.)
+.Bd -literal -offset indent
+TZ="Pacific/Honolulu"
+-	-	-103126	LMT
+1896-01-13	12:01:26	-1030	HST
+1933-04-30	03	-0930	HDT	1
+1933-05-21	11	-1030	HST
+1942-02-09	03	-0930	HWT	1
+1945-08-14	13:30	-0930	HPT	1
+1945-09-30	01	-1030	HST
+1947-06-08	02:30	-10	HST
+.Ed
+.Pp
+Here, local time begins 10 hours, 31 minutes and 26 seconds west of
+UT, and is a standard time abbreviated LMT.
+Immediately after the
+first transition, the date is 1896-01-13 and the time is 12:01:26, and
+the following time interval is 10.5 hours west of UT, a standard time
+abbreviated HST.
+Immediately after the second transition, the date is
+1933-04-30 and the time is 03:00:00 and the following time interval is
+9.5 hours west of UT, is abbreviated HDT, and is daylight saving time.
+Immediately after the last transition the date is 1947-06-08 and the
+time is 02:30:00, and the following time interval is 10 hours west of
+UT, a standard time abbreviated HST.
+.Pp
+Here are excerpts from another example:
+.Bd -literal -offset indent
+TZ="Europe/Astrakhan"
+-	-	+031212	LMT
+1924-04-30	23:47:48	+03
+1930-06-21	01	+04
+1981-04-01	01	+05		1
+1981-09-30	23	+04
+\&...
+2014-10-26	01	+03
+2016-03-27	03	+04
+.Ed
+.Pp
+This time zone is east of UT, so its UT offsets are positive.
+Also,
+many of its time zone abbreviations are omitted since they duplicate
+the text of the UT offset.
+.Sh LIMITATIONS
+Time discontinuities are found by sampling the results returned by
+.Xr localtime 3
+at twelve-hour intervals.
+This works in all real-world cases;
+one can construct artificial time zones for which this fails.
+.Pp
+In the
+.Fl v
+and
+.Fl V
+output,
+.Dq "UT"
+denotes the value returned by
+.Xr gmtime 3 ,
+which uses UTC for modern timestamps and some other UT flavor for
+timestamps that predate the introduction of UTC.
+No attempt is currently made to have the output use
+.Dq "UTC"
+for newer and
+.Dq "UT"
+for older timestamps, partly because the exact date of the
+introduction of UTC is problematic.
+.Sh SEE ALSO
+.Xr tzfile 5 ,
+.Xr zic 8
diff --git a/contrib/tzcode/zdump.c b/contrib/tzcode/zdump.c
new file mode 100644
index 000000000000..d5ddfe537960
--- /dev/null
+++ b/contrib/tzcode/zdump.c
@@ -0,0 +1,1257 @@
+/* Dump time zone data in a textual format.  */
+
+/*
+** This file is in the public domain, so clarified as of
+** 2009-05-17 by Arthur David Olson.
+*/
+
+#include "version.h"
+
+#ifndef NETBSD_INSPIRED
+# define NETBSD_INSPIRED 1
+#endif
+
+#include "private.h"
+#include <stdio.h>
+
+#ifndef HAVE_SNPRINTF
+# define HAVE_SNPRINTF (199901 <= __STDC_VERSION__)
+#endif
+
+#ifndef HAVE_LOCALTIME_R
+# define HAVE_LOCALTIME_R 1
+#endif
+
+#ifndef HAVE_LOCALTIME_RZ
+# ifdef TM_ZONE
+#  define HAVE_LOCALTIME_RZ (NETBSD_INSPIRED && USE_LTZ)
+# else
+#  define HAVE_LOCALTIME_RZ 0
+# endif
+#endif
+
+#ifndef HAVE_TZSET
+# define HAVE_TZSET 1
+#endif
+
+#ifndef ZDUMP_LO_YEAR
+# define ZDUMP_LO_YEAR (-500)
+#endif /* !defined ZDUMP_LO_YEAR */
+
+#ifndef ZDUMP_HI_YEAR
+# define ZDUMP_HI_YEAR 2500
+#endif /* !defined ZDUMP_HI_YEAR */
+
+#define SECSPERNYEAR	(SECSPERDAY * DAYSPERNYEAR)
+#define SECSPERLYEAR	(SECSPERNYEAR + SECSPERDAY)
+#define SECSPER400YEARS	(SECSPERNYEAR * (intmax_t) (300 + 3)	\
+			 + SECSPERLYEAR * (intmax_t) (100 - 3))
+
+/*
+** True if SECSPER400YEARS is known to be representable as an
+** intmax_t.  It's OK that SECSPER400YEARS_FITS can in theory be false
+** even if SECSPER400YEARS is representable, because when that happens
+** the code merely runs a bit more slowly, and this slowness doesn't
+** occur on any practical platform.
+*/
+enum { SECSPER400YEARS_FITS = SECSPERLYEAR <= INTMAX_MAX / 400 };
+
+#if HAVE_GETTEXT
+# include <locale.h> /* for setlocale */
+#endif /* HAVE_GETTEXT */
+
+#if ! HAVE_LOCALTIME_RZ
+# undef  timezone_t
+# define timezone_t char **
+#endif
+
+#if !HAVE_POSIX_DECLS
+extern int	getopt(int argc, char * const argv[],
+			const char * options);
+extern char *	optarg;
+extern int	optind;
+#endif
+
+/* The minimum and maximum finite time values.  */
+enum { atime_shift = CHAR_BIT * sizeof(time_t) - 2 };
+static time_t const absolute_min_time =
+  ((time_t) -1 < 0
+   ? (- ((time_t) ~ (time_t) 0 < 0)
+      - (((time_t) 1 << atime_shift) - 1 + ((time_t) 1 << atime_shift)))
+   : 0);
+static time_t const absolute_max_time =
+  ((time_t) -1 < 0
+   ? (((time_t) 1 << atime_shift) - 1 + ((time_t) 1 << atime_shift))
+   : -1);
+static size_t	longest;
+static char const *progname;
+static bool	warned;
+static bool	errout;
+
+static char const *abbr(struct tm const *);
+static intmax_t	delta(struct tm *, struct tm *) ATTRIBUTE_REPRODUCIBLE;
+static void dumptime(struct tm const *);
+static time_t hunt(timezone_t, time_t, time_t, bool);
+static void show(timezone_t, char *, time_t, bool);
+static void showextrema(timezone_t, char *, time_t, struct tm *, time_t);
+static void showtrans(char const *, struct tm const *, time_t, char const *,
+		      char const *);
+static const char *tformat(void);
+static time_t yeartot(intmax_t) ATTRIBUTE_REPRODUCIBLE;
+
+/* Is C an ASCII digit?  */
+static bool
+is_digit(char c)
+{
+  return '0' <= c && c <= '9';
+}
+
+/* Is A an alphabetic character in the C locale?  */
+static bool
+is_alpha(char a)
+{
+	switch (a) {
+	  default:
+		return false;
+	  case 'A': case 'B': case 'C': case 'D': case 'E': case 'F': case 'G':
+	  case 'H': case 'I': case 'J': case 'K': case 'L': case 'M': case 'N':
+	  case 'O': case 'P': case 'Q': case 'R': case 'S': case 'T': case 'U':
+	  case 'V': case 'W': case 'X': case 'Y': case 'Z':
+	  case 'a': case 'b': case 'c': case 'd': case 'e': case 'f': case 'g':
+	  case 'h': case 'i': case 'j': case 'k': case 'l': case 'm': case 'n':
+	  case 'o': case 'p': case 'q': case 'r': case 's': case 't': case 'u':
+	  case 'v': case 'w': case 'x': case 'y': case 'z':
+		return true;
+	}
+}
+
+static ATTRIBUTE_NORETURN void
+size_overflow(void)
+{
+  fprintf(stderr, _("%s: size overflow\n"), progname);
+  exit(EXIT_FAILURE);
+}
+
+/* Return A + B, exiting if the result would overflow either ptrdiff_t
+   or size_t.  */
+static ATTRIBUTE_REPRODUCIBLE ptrdiff_t
+sumsize(size_t a, size_t b)
+{
+#ifdef ckd_add
+  ptrdiff_t sum;
+  if (!ckd_add(&sum, a, b) /* && sum <= SIZE_MAX */)
+    return sum;
+#else
+  ptrdiff_t sum_max = min(PTRDIFF_MAX, SIZE_MAX);
+  if (a <= sum_max && b <= sum_max - a)
+    return a + b;
+#endif
+  size_overflow();
+}
+
+/* Return a pointer to a newly allocated buffer of size SIZE, exiting
+   on failure.  SIZE should be nonzero.  */
+static void * ATTRIBUTE_MALLOC
+xmalloc(size_t size)
+{
+  void *p = malloc(size);
+  if (!p) {
+    fprintf(stderr, _("%s: Memory exhausted\n"), progname);
+    exit(EXIT_FAILURE);
+  }
+  return p;
+}
+
+#if ! HAVE_TZSET
+# undef tzset
+# define tzset zdump_tzset
+static void tzset(void) { }
+#endif
+
+/* Assume gmtime_r works if localtime_r does.
+   A replacement localtime_r is defined below if needed.  */
+#if ! HAVE_LOCALTIME_R
+
+# undef gmtime_r
+# define gmtime_r zdump_gmtime_r
+
+static struct tm *
+gmtime_r(time_t *tp, struct tm *tmp)
+{
+  struct tm *r = gmtime(tp);
+  if (r) {
+    *tmp = *r;
+    r = tmp;
+  }
+  return r;
+}
+
+#endif
+
+/* Platforms with TM_ZONE don't need tzname, so they can use the
+   faster localtime_rz or localtime_r if available.  */
+
+#if defined TM_ZONE && HAVE_LOCALTIME_RZ
+# define USE_LOCALTIME_RZ true
+#else
+# define USE_LOCALTIME_RZ false
+#endif
+
+#if ! USE_LOCALTIME_RZ
+
+# if !defined TM_ZONE || ! HAVE_LOCALTIME_R || ! HAVE_TZSET
+#  undef localtime_r
+#  define localtime_r zdump_localtime_r
+static struct tm *
+localtime_r(time_t *tp, struct tm *tmp)
+{
+  struct tm *r = localtime(tp);
+  if (r) {
+    *tmp = *r;
+    r = tmp;
+  }
+  return r;
+}
+# endif
+
+# undef localtime_rz
+# define localtime_rz zdump_localtime_rz
+static struct tm *
+localtime_rz(timezone_t rz __unused, time_t *tp, struct tm *tmp)
+{
+  return localtime_r(tp, tmp);
+}
+
+# ifdef TYPECHECK
+#  undef mktime_z
+#  define mktime_z zdump_mktime_z
+static time_t
+mktime_z(timezone_t tz, struct tm *tmp)
+{
+  return mktime(tmp);
+}
+# endif
+
+# undef tzalloc
+# undef tzfree
+# define tzalloc zdump_tzalloc
+# define tzfree zdump_tzfree
+
+static timezone_t
+tzalloc(char const *val)
+{
+# if HAVE_SETENV
+  if (setenv("TZ", val, 1) != 0) {
+    perror("setenv");
+    exit(EXIT_FAILURE);
+  }
+  tzset();
+  return &optarg;  /* Any valid non-null char ** will do.  */
+# else
+  enum { TZeqlen = 3 };
+  static char const TZeq[TZeqlen] = "TZ=";
+  static char **fakeenv;
+  static ptrdiff_t fakeenv0size;
+  void *freeable = NULL;
+  char **env = fakeenv, **initial_environ;
+  size_t valsize = strlen(val) + 1;
+  if (fakeenv0size < valsize) {
+    char **e = environ, **to;
+    ptrdiff_t initial_nenvptrs = 1;  /* Counting the trailing NULL pointer.  */
+
+    while (*e++) {
+#  ifdef ckd_add
+      if (ckd_add(&initial_nenvptrs, initial_envptrs, 1)
+	  || SIZE_MAX < initial_envptrs)
+	size_overflow();
+#  else
+      if (initial_nenvptrs == min(PTRDIFF_MAX, SIZE_MAX) / sizeof *environ)
+	size_overflow();
+      initial_nenvptrs++;
+#  endif
+    }
+    fakeenv0size = sumsize(valsize, valsize);
+    fakeenv0size = max(fakeenv0size, 64);
+    freeable = env;
+    fakeenv = env =
+      xmalloc(sumsize(sumsize(sizeof *environ,
+			      initial_nenvptrs * sizeof *environ),
+		      sumsize(TZeqlen, fakeenv0size)));
+    to = env + 1;
+    for (e = environ; (*to = *e); e++)
+      to += strncmp(*e, TZeq, TZeqlen) != 0;
+    env[0] = memcpy(to + 1, TZeq, TZeqlen);
+  }
+  memcpy(env[0] + TZeqlen, val, valsize);
+  initial_environ = environ;
+  environ = env;
+  tzset();
+  free(freeable);
+  return initial_environ;
+# endif
+}
+
+static void
+tzfree(timezone_t initial_environ)
+{
+# if !HAVE_SETENV
+  environ = initial_environ;
+  tzset();
+# else
+  (void)initial_environ;
+# endif
+}
+#endif /* ! USE_LOCALTIME_RZ */
+
+/* A UT time zone, and its initializer.  */
+static timezone_t gmtz;
+static void
+gmtzinit(void)
+{
+  if (USE_LOCALTIME_RZ) {
+    /* Try "GMT" first to find out whether this is one of the rare
+       platforms where time_t counts leap seconds; this works due to
+       the "Zone GMT 0 - GMT" line in the "etcetera" file.  If "GMT"
+       fails, fall back on "GMT0" which might be similar due to the
+       "Link GMT GMT0" line in the "backward" file, and which
+       should work on all POSIX platforms.  The rest of zdump does not
+       use the "GMT" abbreviation that comes from this setting, so it
+       is OK to use "GMT" here rather than the more-modern "UTC" which
+       would not work on platforms that omit the "backward" file.  */
+    gmtz = tzalloc("GMT");
+    if (!gmtz) {
+      static char const gmt0[] = "GMT0";
+      gmtz = tzalloc(gmt0);
+      if (!gmtz) {
+	perror(gmt0);
+	exit(EXIT_FAILURE);
+      }
+    }
+  }
+}
+
+/* Convert *TP to UT, storing the broken-down time into *TMP.
+   Return TMP if successful, NULL otherwise.  This is like gmtime_r(TP, TMP),
+   except typically faster if USE_LOCALTIME_RZ.  */
+static struct tm *
+my_gmtime_r(time_t *tp, struct tm *tmp)
+{
+  return USE_LOCALTIME_RZ ? localtime_rz(gmtz, tp, tmp) : gmtime_r(tp, tmp);
+}
+
+#ifndef TYPECHECK
+# define my_localtime_rz localtime_rz
+#else /* !defined TYPECHECK */
+
+static struct tm *
+my_localtime_rz(timezone_t tz, time_t *tp, struct tm *tmp)
+{
+	tmp = localtime_rz(tz, tp, tmp);
+	if (tmp) {
+		struct tm	tm;
+		register time_t	t;
+
+		tm = *tmp;
+		t = mktime_z(tz, &tm);
+		if (t != *tp) {
+			fflush(stdout);
+			fprintf(stderr, "\n%s: ", progname);
+			fprintf(stderr, tformat(), *tp);
+			fprintf(stderr, " ->");
+			fprintf(stderr, " year=%d", tmp->tm_year);
+			fprintf(stderr, " mon=%d", tmp->tm_mon);
+			fprintf(stderr, " mday=%d", tmp->tm_mday);
+			fprintf(stderr, " hour=%d", tmp->tm_hour);
+			fprintf(stderr, " min=%d", tmp->tm_min);
+			fprintf(stderr, " sec=%d", tmp->tm_sec);
+			fprintf(stderr, " isdst=%d", tmp->tm_isdst);
+			fprintf(stderr, " -> ");
+			fprintf(stderr, tformat(), t);
+			fprintf(stderr, "\n");
+			errout = true;
+		}
+	}
+	return tmp;
+}
+#endif /* !defined TYPECHECK */
+
+static void
+abbrok(const char *const abbrp, const char *const zone)
+{
+	register const char *	cp;
+	register const char *	wp;
+
+	if (warned)
+		return;
+	cp = abbrp;
+	while (is_alpha(*cp) || is_digit(*cp) || *cp == '-' || *cp == '+')
+		++cp;
+	if (*cp)
+	  wp = _("has characters other than ASCII alphanumerics, '-' or '+'");
+	else if (cp - abbrp < 3)
+	  wp = _("has fewer than 3 characters");
+	else if (cp - abbrp > 6)
+	  wp = _("has more than 6 characters");
+	else
+	  return;
+	fflush(stdout);
+	fprintf(stderr,
+		_("%s: warning: zone \"%s\" abbreviation \"%s\" %s\n"),
+		progname, zone, abbrp, wp);
+	warned = errout = true;
+}
+
+/* Return a time zone abbreviation.  If the abbreviation needs to be
+   saved, use *BUF (of size *BUFALLOC) to save it, and return the
+   abbreviation in the possibly-reallocated *BUF.  Otherwise, just
+   return the abbreviation.  Get the abbreviation from TMP.
+   Exit on memory allocation failure.  */
+static char const *
+saveabbr(char **buf, ptrdiff_t *bufalloc, struct tm const *tmp)
+{
+  char const *ab = abbr(tmp);
+  if (HAVE_LOCALTIME_RZ)
+    return ab;
+  else {
+    size_t ablen = strlen(ab);
+    if ((size_t)*bufalloc <= ablen) {
+      free(*buf);
+
+      /* Make the new buffer at least twice as long as the old,
+	 to avoid O(N**2) behavior on repeated calls.  */
+      *bufalloc = sumsize(*bufalloc, ablen + 1);
+
+      *buf = xmalloc(*bufalloc);
+    }
+    return strcpy(*buf, ab);
+  }
+}
+
+static void
+close_file(FILE *stream)
+{
+  char const *e = (ferror(stream) ? _("I/O error")
+		   : fclose(stream) != 0 ? strerror(errno) : NULL);
+  if (e) {
+    fprintf(stderr, "%s: %s\n", progname, e);
+    exit(EXIT_FAILURE);
+  }
+}
+
+static void
+usage(FILE * const stream, const int status)
+{
+	fprintf(stream,
+_("%s: usage: %s OPTIONS TIMEZONE ...\n"
+  "Options include:\n"
+  "  -c [L,]U   Start at year L (default -500), end before year U (default 2500)\n"
+  "  -t [L,]U   Start at time L, end before time U (in seconds since 1970)\n"
+  "  -i         List transitions briefly (format is experimental)\n" \
+  "  -v         List transitions verbosely\n"
+  "  -V         List transitions a bit less verbosely\n"
+  "  --help     Output this help\n"
+  "  --version  Output version info\n"
+  "\n"
+  "Report bugs to %s.\n"),
+		progname, progname, REPORT_BUGS_TO);
+	if (status == EXIT_SUCCESS)
+	  close_file(stream);
+	exit(status);
+}
+
+int
+main(int argc, char *argv[])
+{
+	/* These are static so that they're initially zero.  */
+	static char *		abbrev;
+	static ptrdiff_t	abbrevsize;
+
+	register int		i;
+	register bool		vflag;
+	register bool		Vflag;
+	register char *		cutarg;
+	register char *		cuttimes;
+	register time_t		cutlotime;
+	register time_t		cuthitime;
+	time_t			now;
+	bool iflag = false;
+
+	cutlotime = absolute_min_time;
+	cuthitime = absolute_max_time;
+#if HAVE_GETTEXT
+	setlocale(LC_ALL, "");
+# ifdef TZ_DOMAINDIR
+	bindtextdomain(TZ_DOMAIN, TZ_DOMAINDIR);
+# endif /* defined TEXTDOMAINDIR */
+	textdomain(TZ_DOMAIN);
+#endif /* HAVE_GETTEXT */
+	progname = argv[0] ? argv[0] : "zdump";
+	for (i = 1; i < argc; ++i)
+		if (strcmp(argv[i], "--version") == 0) {
+			printf("zdump %s%s\n", PKGVERSION, TZVERSION);
+			return EXIT_SUCCESS;
+		} else if (strcmp(argv[i], "--help") == 0) {
+			usage(stdout, EXIT_SUCCESS);
+		}
+	vflag = Vflag = false;
+	cutarg = cuttimes = NULL;
+	for (;;)
+	  switch (getopt(argc, argv, "c:it:vV")) {
+	  case 'c': cutarg = optarg; break;
+	  case 't': cuttimes = optarg; break;
+	  case 'i': iflag = true; break;
+	  case 'v': vflag = true; break;
+	  case 'V': Vflag = true; break;
+	  case -1:
+	    if (! (optind == argc - 1 && strcmp(argv[optind], "=") == 0))
+	      goto arg_processing_done;
+	    ATTRIBUTE_FALLTHROUGH;
+	  default:
+	    usage(stderr, EXIT_FAILURE);
+	  }
+ arg_processing_done:;
+
+	if (iflag | vflag | Vflag) {
+		intmax_t	lo;
+		intmax_t	hi;
+		char *loend, *hiend;
+		register intmax_t cutloyear = ZDUMP_LO_YEAR;
+		register intmax_t cuthiyear = ZDUMP_HI_YEAR;
+		if (cutarg != NULL) {
+			lo = strtoimax(cutarg, &loend, 10);
+			if (cutarg != loend && !*loend) {
+				hi = lo;
+				cuthiyear = hi;
+			} else if (cutarg != loend && *loend == ','
+				   && (hi = strtoimax(loend + 1, &hiend, 10),
+				       loend + 1 != hiend && !*hiend)) {
+				cutloyear = lo;
+				cuthiyear = hi;
+			} else {
+				fprintf(stderr, _("%s: wild -c argument %s\n"),
+					progname, cutarg);
+				return EXIT_FAILURE;
+			}
+		}
+		if (cutarg != NULL || cuttimes == NULL) {
+			cutlotime = yeartot(cutloyear);
+			cuthitime = yeartot(cuthiyear);
+		}
+		if (cuttimes != NULL) {
+			lo = strtoimax(cuttimes, &loend, 10);
+			if (cuttimes != loend && !*loend) {
+				hi = lo;
+				if (hi < cuthitime) {
+					if (hi < absolute_min_time + 1)
+					  hi = absolute_min_time + 1;
+					cuthitime = hi;
+				}
+			} else if (cuttimes != loend && *loend == ','
+				   && (hi = strtoimax(loend + 1, &hiend, 10),
+				       loend + 1 != hiend && !*hiend)) {
+				if (cutlotime < lo) {
+					if (absolute_max_time < lo)
+						lo = absolute_max_time;
+					cutlotime = lo;
+				}
+				if (hi < cuthitime) {
+					if (hi < absolute_min_time + 1)
+					  hi = absolute_min_time + 1;
+					cuthitime = hi;
+				}
+			} else {
+				fprintf(stderr,
+					_("%s: wild -t argument %s\n"),
+					progname, cuttimes);
+				return EXIT_FAILURE;
+			}
+		}
+	}
+	gmtzinit();
+	if (iflag | vflag | Vflag)
+	  now = 0;
+	else {
+	  now = time(NULL);
+	  now |= !now;
+	}
+	longest = 0;
+	for (i = optind; i < argc; i++) {
+	  size_t arglen = strlen(argv[i]);
+	  if (longest < arglen)
+	    longest = min(arglen, INT_MAX);
+	}
+
+	for (i = optind; i < argc; ++i) {
+		timezone_t tz = tzalloc(argv[i]);
+		char const *ab;
+		time_t t;
+		struct tm tm, newtm;
+		bool tm_ok;
+		if (!tz) {
+		  perror(argv[i]);
+		  return EXIT_FAILURE;
+		}
+		if (now) {
+			show(tz, argv[i], now, false);
+			tzfree(tz);
+			continue;
+		}
+		warned = false;
+		t = absolute_min_time;
+		if (! (iflag | Vflag)) {
+			show(tz, argv[i], t, true);
+			if (my_localtime_rz(tz, &t, &tm) == NULL
+			    && t < cutlotime) {
+				time_t newt = cutlotime;
+				if (my_localtime_rz(tz, &newt, &newtm) != NULL)
+				  showextrema(tz, argv[i], t, NULL, newt);
+			}
+		}
+		if (t + 1 < cutlotime)
+		  t = cutlotime - 1;
+		tm_ok = my_localtime_rz(tz, &t, &tm) != NULL;
+		if (tm_ok) {
+		  ab = saveabbr(&abbrev, &abbrevsize, &tm);
+		  if (iflag) {
+		    showtrans("\nTZ=%f", &tm, t, ab, argv[i]);
+		    showtrans("-\t-\t%Q", &tm, t, ab, argv[i]);
+		  }
+		} else
+		  ab = NULL;
+		while (t < cuthitime - 1) {
+		  time_t newt = ((t < absolute_max_time - SECSPERDAY / 2
+				  && t + SECSPERDAY / 2 < cuthitime - 1)
+				 ? t + SECSPERDAY / 2
+				 : cuthitime - 1);
+		  struct tm *newtmp = localtime_rz(tz, &newt, &newtm);
+		  bool newtm_ok = newtmp != NULL;
+		  if (tm_ok != newtm_ok
+		      || (ab && (delta(&newtm, &tm) != newt - t
+				 || newtm.tm_isdst != tm.tm_isdst
+				 || strcmp(abbr(&newtm), ab) != 0))) {
+		    newt = hunt(tz, t, newt, false);
+		    newtmp = localtime_rz(tz, &newt, &newtm);
+		    newtm_ok = newtmp != NULL;
+		    if (iflag)
+		      showtrans("%Y-%m-%d\t%L\t%Q", newtmp, newt,
+				newtm_ok ? abbr(&newtm) : NULL, argv[i]);
+		    else {
+		      show(tz, argv[i], newt - 1, true);
+		      show(tz, argv[i], newt, true);
+		    }
+		  }
+		  t = newt;
+		  tm_ok = newtm_ok;
+		  if (newtm_ok) {
+		    ab = saveabbr(&abbrev, &abbrevsize, &newtm);
+		    tm = newtm;
+		  }
+		}
+		if (! (iflag | Vflag)) {
+			time_t newt = absolute_max_time;
+			t = cuthitime;
+			if (t < newt) {
+			  struct tm *tmp = my_localtime_rz(tz, &t, &tm);
+			  if (tmp != NULL
+			      && my_localtime_rz(tz, &newt, &newtm) == NULL)
+			    showextrema(tz, argv[i], t, tmp, newt);
+			}
+			show(tz, argv[i], absolute_max_time, true);
+		}
+		tzfree(tz);
+	}
+	close_file(stdout);
+	if (errout && (ferror(stderr) || fclose(stderr) != 0))
+	  return EXIT_FAILURE;
+	return EXIT_SUCCESS;
+}
+
+static time_t
+yeartot(intmax_t y)
+{
+	register intmax_t	myy, seconds, years;
+	register time_t		t;
+
+	myy = EPOCH_YEAR;
+	t = 0;
+	while (myy < y) {
+		if (SECSPER400YEARS_FITS && 400 <= y - myy) {
+			intmax_t diff400 = (y - myy) / 400;
+			if (INTMAX_MAX / SECSPER400YEARS < diff400)
+				return absolute_max_time;
+			seconds = diff400 * SECSPER400YEARS;
+			years = diff400 * 400;
+                } else {
+			seconds = isleap(myy) ? SECSPERLYEAR : SECSPERNYEAR;
+			years = 1;
+		}
+		myy += years;
+		if (t > absolute_max_time - seconds)
+			return absolute_max_time;
+		t += seconds;
+	}
+	while (y < myy) {
+		if (SECSPER400YEARS_FITS && y + 400 <= myy && myy < 0) {
+			intmax_t diff400 = (myy - y) / 400;
+			if (INTMAX_MAX / SECSPER400YEARS < diff400)
+				return absolute_min_time;
+			seconds = diff400 * SECSPER400YEARS;
+			years = diff400 * 400;
+		} else {
+			seconds = isleap(myy - 1) ? SECSPERLYEAR : SECSPERNYEAR;
+			years = 1;
+		}
+		myy -= years;
+		if (t < absolute_min_time + seconds)
+			return absolute_min_time;
+		t -= seconds;
+	}
+	return t;
+}
+
+/* Search for a discontinuity in timezone TZ, in the
+   timestamps ranging from LOT through HIT.  LOT and HIT disagree
+   about some aspect of timezone.  If ONLY_OK, search only for
+   definedness changes, i.e., localtime succeeds on one side of the
+   transition but fails on the other side.  Return the timestamp just
+   before the transition from LOT's settings.  */
+
+static time_t
+hunt(timezone_t tz, time_t lot, time_t hit, bool only_ok)
+{
+	static char *		loab;
+	static ptrdiff_t	loabsize;
+	struct tm		lotm;
+	struct tm		tm;
+
+	/* Convert LOT into a broken-down time here, even though our
+	   caller already did that.  On platforms without TM_ZONE,
+	   tzname may have been altered since our caller broke down
+	   LOT, and tzname needs to be changed back.  */
+	bool lotm_ok = my_localtime_rz(tz, &lot, &lotm) != NULL;
+	bool tm_ok;
+	char const *ab = lotm_ok ? saveabbr(&loab, &loabsize, &lotm) : NULL;
+
+	for ( ; ; ) {
+		/* T = average of LOT and HIT, rounding down.
+		   Avoid overflow, even on oddball C89 platforms
+		   where / rounds down and TIME_T_MIN == -TIME_T_MAX
+		   so lot / 2 + hit / 2 might overflow.  */
+		time_t t = (lot / 2
+			    - ((lot % 2 + hit % 2) < 0)
+			    + ((lot % 2 + hit % 2) == 2)
+			    + hit / 2);
+		if (t == lot)
+			break;
+		tm_ok = my_localtime_rz(tz, &t, &tm) != NULL;
+		if (lotm_ok == tm_ok
+		    && (only_ok
+			|| (ab && tm.tm_isdst == lotm.tm_isdst
+			    && delta(&tm, &lotm) == t - lot
+			    && strcmp(abbr(&tm), ab) == 0))) {
+		  lot = t;
+		  if (tm_ok)
+		    lotm = tm;
+		} else	hit = t;
+	}
+	return hit;
+}
+
+/*
+** Thanks to Paul Eggert for logic used in delta_nonneg.
+*/
+
+static intmax_t
+delta_nonneg(struct tm *newp, struct tm *oldp)
+{
+	intmax_t oldy = oldp->tm_year;
+	int cycles = (newp->tm_year - oldy) / YEARSPERREPEAT;
+	intmax_t sec = SECSPERREPEAT, result = cycles * sec;
+	int tmy = oldp->tm_year + cycles * YEARSPERREPEAT;
+	for ( ; tmy < newp->tm_year; ++tmy)
+		result += DAYSPERNYEAR + isleap_sum(tmy, TM_YEAR_BASE);
+	result += newp->tm_yday - oldp->tm_yday;
+	result *= HOURSPERDAY;
+	result += newp->tm_hour - oldp->tm_hour;
+	result *= MINSPERHOUR;
+	result += newp->tm_min - oldp->tm_min;
+	result *= SECSPERMIN;
+	result += newp->tm_sec - oldp->tm_sec;
+	return result;
+}
+
+static intmax_t
+delta(struct tm *newp, struct tm *oldp)
+{
+  return (newp->tm_year < oldp->tm_year
+	  ? -delta_nonneg(oldp, newp)
+	  : delta_nonneg(newp, oldp));
+}
+
+#ifndef TM_GMTOFF
+/* Return A->tm_yday, adjusted to compare it fairly to B->tm_yday.
+   Assume A and B differ by at most one year.  */
+static int
+adjusted_yday(struct tm const *a, struct tm const *b)
+{
+  int yday = a->tm_yday;
+  if (b->tm_year < a->tm_year)
+    yday += 365 + isleap_sum(b->tm_year, TM_YEAR_BASE);
+  return yday;
+}
+#endif
+
+/* If A is the broken-down local time and B the broken-down UT for
+   the same instant, return A's UT offset in seconds, where positive
+   offsets are east of Greenwich.  On failure, return LONG_MIN.
+
+   If T is nonnull, *T is the timestamp that corresponds to A; call
+   my_gmtime_r and use its result instead of B.  Otherwise, B is the
+   possibly nonnull result of an earlier call to my_gmtime_r.  */
+static long
+gmtoff(struct tm const *a, ATTRIBUTE_MAYBE_UNUSED time_t *t,
+       ATTRIBUTE_MAYBE_UNUSED struct tm const *b)
+{
+#ifdef TM_GMTOFF
+  return a->TM_GMTOFF;
+#else
+  struct tm tm;
+  if (t)
+    b = my_gmtime_r(t, &tm);
+  if (! b)
+    return LONG_MIN;
+  else {
+    int ayday = adjusted_yday(a, b);
+    int byday = adjusted_yday(b, a);
+    int days = ayday - byday;
+    long hours = a->tm_hour - b->tm_hour + 24 * days;
+    long minutes = a->tm_min - b->tm_min + 60 * hours;
+    long seconds = a->tm_sec - b->tm_sec + 60 * minutes;
+    return seconds;
+  }
+#endif
+}
+
+static void
+show(timezone_t tz, char *zone, time_t t, bool v)
+{
+	register struct tm *	tmp;
+	register struct tm *	gmtmp;
+	struct tm tm, gmtm;
+
+	printf("%-*s  ", (int)longest, zone);
+	if (v) {
+		gmtmp = my_gmtime_r(&t, &gmtm);
+		if (gmtmp == NULL) {
+			printf(tformat(), t);
+			printf(_(" (gmtime failed)"));
+		} else {
+			dumptime(gmtmp);
+			printf(" UT");
+		}
+		printf(" = ");
+	}
+	tmp = my_localtime_rz(tz, &t, &tm);
+	if (tmp == NULL) {
+		printf(tformat(), t);
+		printf(_(" (localtime failed)"));
+	} else {
+		dumptime(tmp);
+		if (*abbr(tmp) != '\0')
+			printf(" %s", abbr(tmp));
+		if (v) {
+			long off = gmtoff(tmp, NULL, gmtmp);
+			printf(" isdst=%d", tmp->tm_isdst);
+			if (off != LONG_MIN)
+			  printf(" gmtoff=%ld", off);
+		}
+	}
+	printf("\n");
+	if (tmp != NULL && *abbr(tmp) != '\0')
+		abbrok(abbr(tmp), zone);
+}
+
+/* Show timestamps just before and just after a transition between
+   defined and undefined (or vice versa) in either localtime or
+   gmtime.  These transitions are for timezone TZ with name ZONE, in
+   the range from LO (with broken-down time LOTMP if that is nonnull)
+   through HI.  LO and HI disagree on definedness.  */
+
+static void
+showextrema(timezone_t tz, char *zone, time_t lo, struct tm *lotmp, time_t hi)
+{
+  struct tm localtm[2], gmtm[2];
+  time_t t, boundary = hunt(tz, lo, hi, true);
+  bool old = false;
+  hi = (SECSPERDAY < hi - boundary
+	? boundary + SECSPERDAY
+	: hi + (hi < TIME_T_MAX));
+  if (SECSPERDAY < boundary - lo) {
+    lo = boundary - SECSPERDAY;
+    lotmp = my_localtime_rz(tz, &lo, &localtm[old]);
+  }
+  if (lotmp)
+    localtm[old] = *lotmp;
+  else
+    localtm[old].tm_sec = -1;
+  if (! my_gmtime_r(&lo, &gmtm[old]))
+    gmtm[old].tm_sec = -1;
+
+  /* Search sequentially for definedness transitions.  Although this
+     could be sped up by refining 'hunt' to search for either
+     localtime or gmtime definedness transitions, it hardly seems
+     worth the trouble.  */
+  for (t = lo + 1; t < hi; t++) {
+    bool new = !old;
+    if (! my_localtime_rz(tz, &t, &localtm[new]))
+      localtm[new].tm_sec = -1;
+    if (! my_gmtime_r(&t, &gmtm[new]))
+      gmtm[new].tm_sec = -1;
+    if (((localtm[old].tm_sec < 0) != (localtm[new].tm_sec < 0))
+	| ((gmtm[old].tm_sec < 0) != (gmtm[new].tm_sec < 0))) {
+      show(tz, zone, t - 1, true);
+      show(tz, zone, t, true);
+    }
+    old = new;
+  }
+}
+
+#if HAVE_SNPRINTF
+# define my_snprintf snprintf
+#else
+# include <stdarg.h>
+
+/* A substitute for snprintf that is good enough for zdump.  */
+static int ATTRIBUTE_FORMAT((printf, 3, 4))
+my_snprintf(char *s, size_t size, char const *format, ...)
+{
+  int n;
+  va_list args;
+  char const *arg;
+  size_t arglen, slen;
+  char buf[1024];
+  va_start(args, format);
+  if (strcmp(format, "%s") == 0) {
+    arg = va_arg(args, char const *);
+    arglen = strlen(arg);
+  } else {
+    n = vsprintf(buf, format, args);
+    if (n < 0) {
+      va_end(args);
+      return n;
+    }
+    arg = buf;
+    arglen = n;
+  }
+  slen = arglen < size ? arglen : size - 1;
+  memcpy(s, arg, slen);
+  s[slen] = '\0';
+  n = arglen <= INT_MAX ? arglen : -1;
+  va_end(args);
+  return n;
+}
+#endif
+
+/* Store into BUF, of size SIZE, a formatted local time taken from *TM.
+   Use ISO 8601 format +HH:MM:SS.  Omit :SS if SS is zero, and omit
+   :MM too if MM is also zero.
+
+   Return the length of the resulting string.  If the string does not
+   fit, return the length that the string would have been if it had
+   fit; do not overrun the output buffer.  */
+static int
+format_local_time(char *buf, ptrdiff_t size, struct tm const *tm)
+{
+  int ss = tm->tm_sec, mm = tm->tm_min, hh = tm->tm_hour;
+  return (ss
+	  ? my_snprintf(buf, size, "%02d:%02d:%02d", hh, mm, ss)
+	  : mm
+	  ? my_snprintf(buf, size, "%02d:%02d", hh, mm)
+	  : my_snprintf(buf, size, "%02d", hh));
+}
+
+/* Store into BUF, of size SIZE, a formatted UT offset for the
+   localtime *TM corresponding to time T.  Use ISO 8601 format
+   +HHMMSS, or -HHMMSS for timestamps west of Greenwich; use the
+   format -00 for unknown UT offsets.  If the hour needs more than
+   two digits to represent, extend the length of HH as needed.
+   Otherwise, omit SS if SS is zero, and omit MM too if MM is also
+   zero.
+
+   Return the length of the resulting string, or -1 if the result is
+   not representable as a string.  If the string does not fit, return
+   the length that the string would have been if it had fit; do not
+   overrun the output buffer.  */
+static int
+format_utc_offset(char *buf, ptrdiff_t size, struct tm const *tm, time_t t)
+{
+  long off = gmtoff(tm, &t, NULL);
+  char sign = ((off < 0
+		|| (off == 0
+		    && (*abbr(tm) == '-' || strcmp(abbr(tm), "zzz") == 0)))
+	       ? '-' : '+');
+  long hh;
+  int mm, ss;
+  if (off < 0)
+    {
+      if (off == LONG_MIN)
+	return -1;
+      off = -off;
+    }
+  ss = off % 60;
+  mm = off / 60 % 60;
+  hh = off / 60 / 60;
+  return (ss || 100 <= hh
+	  ? my_snprintf(buf, size, "%c%02ld%02d%02d", sign, hh, mm, ss)
+	  : mm
+	  ? my_snprintf(buf, size, "%c%02ld%02d", sign, hh, mm)
+	  : my_snprintf(buf, size, "%c%02ld", sign, hh));
+}
+
+/* Store into BUF (of size SIZE) a quoted string representation of P.
+   If the representation's length is less than SIZE, return the
+   length; the representation is not null terminated.  Otherwise
+   return SIZE, to indicate that BUF is too small.  */
+static ptrdiff_t
+format_quoted_string(char *buf, ptrdiff_t size, char const *p)
+{
+  char *b = buf;
+  ptrdiff_t s = size;
+  if (!s)
+    return size;
+  *b++ = '"', s--;
+  for (;;) {
+    char c = *p++;
+    if (s <= 1)
+      return size;
+    switch (c) {
+    default: *b++ = c, s--; continue;
+    case '\0': *b++ = '"', s--; return size - s;
+    case '"': case '\\': break;
+    case ' ': c = 's'; break;
+    case '\f': c = 'f'; break;
+    case '\n': c = 'n'; break;
+    case '\r': c = 'r'; break;
+    case '\t': c = 't'; break;
+    case '\v': c = 'v'; break;
+    }
+    *b++ = '\\', *b++ = c, s -= 2;
+  }
+}
+
+/* Store into BUF (of size SIZE) a timestamp formatted by TIME_FMT.
+   TM is the broken-down time, T the seconds count, AB the time zone
+   abbreviation, and ZONE_NAME the zone name.  Return true if
+   successful, false if the output would require more than SIZE bytes.
+   TIME_FMT uses the same format that strftime uses, with these
+   additions:
+
+   %f zone name
+   %L local time as per format_local_time
+   %Q like "U\t%Z\tD" where U is the UT offset as for format_utc_offset
+      and D is the isdst flag; except omit D if it is zero, omit %Z if
+      it equals U, quote and escape %Z if it contains nonalphabetics,
+      and omit any trailing tabs.  */
+
+static bool
+istrftime(char *buf, ptrdiff_t size, char const *time_fmt,
+	  struct tm const *tm, time_t t, char const *ab, char const *zone_name)
+{
+  char *b = buf;
+  ptrdiff_t s = size;
+  char const *f = time_fmt, *p;
+
+  for (p = f; ; p++)
+    if (*p == '%' && p[1] == '%')
+      p++;
+    else if (!*p
+	     || (*p == '%'
+		 && (p[1] == 'f' || p[1] == 'L' || p[1] == 'Q'))) {
+      ptrdiff_t formatted_len;
+      ptrdiff_t f_prefix_len = p - f;
+      ptrdiff_t f_prefix_copy_size = sumsize(f_prefix_len, 2);
+      char fbuf[100];
+      bool oversized = sizeof fbuf <= (size_t)f_prefix_copy_size;
+      char *f_prefix_copy = oversized ? xmalloc(f_prefix_copy_size) : fbuf;
+      memcpy(f_prefix_copy, f, f_prefix_len);
+      strcpy(f_prefix_copy + f_prefix_len, "X");
+      formatted_len = strftime(b, s, f_prefix_copy, tm);
+      if (oversized)
+	free(f_prefix_copy);
+      if (formatted_len == 0)
+	return false;
+      formatted_len--;
+      b += formatted_len, s -= formatted_len;
+      if (!*p++)
+	break;
+      switch (*p) {
+      case 'f':
+	formatted_len = format_quoted_string(b, s, zone_name);
+	break;
+      case 'L':
+	formatted_len = format_local_time(b, s, tm);
+	break;
+      case 'Q':
+	{
+	  bool show_abbr;
+	  int offlen = format_utc_offset(b, s, tm, t);
+	  if (! (0 <= offlen && offlen < s))
+	    return false;
+	  show_abbr = strcmp(b, ab) != 0;
+	  b += offlen, s -= offlen;
+	  if (show_abbr) {
+	    char const *abp;
+	    ptrdiff_t len;
+	    if (s <= 1)
+	      return false;
+	    *b++ = '\t', s--;
+	    for (abp = ab; is_alpha(*abp); abp++)
+	      continue;
+	    len = (!*abp && *ab
+		   ? my_snprintf(b, s, "%s", ab)
+		   : format_quoted_string(b, s, ab));
+	    if (s <= len)
+	      return false;
+	    b += len, s -= len;
+	  }
+	  formatted_len
+	    = (tm->tm_isdst
+	       ? my_snprintf(b, s, &"\t\t%d"[show_abbr], tm->tm_isdst)
+	       : 0);
+	}
+	break;
+      }
+      if (s <= formatted_len)
+	return false;
+      b += formatted_len, s -= formatted_len;
+      f = p + 1;
+    }
+  *b = '\0';
+  return true;
+}
+
+/* Show a time transition.  */
+static void
+showtrans(char const *time_fmt, struct tm const *tm, time_t t, char const *ab,
+	  char const *zone_name)
+{
+  if (!tm) {
+    printf(tformat(), t);
+    putchar('\n');
+  } else {
+    char stackbuf[1000];
+    ptrdiff_t size = sizeof stackbuf;
+    char *buf = stackbuf;
+    char *bufalloc = NULL;
+    while (! istrftime(buf, size, time_fmt, tm, t, ab, zone_name)) {
+      size = sumsize(size, size);
+      free(bufalloc);
+      buf = bufalloc = xmalloc(size);
+    }
+    puts(buf);
+    free(bufalloc);
+  }
+}
+
+static char const *
+abbr(struct tm const *tmp)
+{
+#ifdef TM_ZONE
+	return tmp->TM_ZONE;
+#else
+# if HAVE_TZNAME
+	if (0 <= tmp->tm_isdst && tzname[0 < tmp->tm_isdst])
+	  return tzname[0 < tmp->tm_isdst];
+# endif
+	return "";
+#endif
+}
+
+/*
+** The code below can fail on certain theoretical systems;
+** it works on all known real-world systems as of 2022-01-25.
+*/
+
+static const char *
+tformat(void)
+{
+#if HAVE_GENERIC
+	/* C11-style _Generic is more likely to return the correct
+	   format when distinct types have the same size.  */
+	char const *fmt =
+	  _Generic(+ (time_t) 0,
+		   int: "%d", long: "%ld", long long: "%lld",
+		   unsigned: "%u", unsigned long: "%lu",
+		   unsigned long long: "%llu",
+		   default: NULL);
+	if (fmt)
+	  return fmt;
+	fmt = _Generic((time_t) 0,
+		       intmax_t: "%"PRIdMAX, uintmax_t: "%"PRIuMAX,
+		       default: NULL);
+	if (fmt)
+	  return fmt;
+#endif
+	if (0 > (time_t) -1) {		/* signed */
+		if (sizeof(time_t) == sizeof(intmax_t))
+			return "%"PRIdMAX;
+		if (sizeof(time_t) > sizeof(long))
+			return "%lld";
+		if (sizeof(time_t) > sizeof(int))
+			return "%ld";
+		return "%d";
+	}
+#ifdef PRIuMAX
+	if (sizeof(time_t) == sizeof(uintmax_t))
+		return "%"PRIuMAX;
+#endif
+	if (sizeof(time_t) > sizeof(unsigned long))
+		return "%llu";
+	if (sizeof(time_t) > sizeof(unsigned int))
+		return "%lu";
+	return "%u";
+}
+
+static void
+dumptime(register const struct tm *timeptr)
+{
+	static const char	wday_name[][4] = {
+		"Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"
+	};
+	static const char	mon_name[][4] = {
+		"Jan", "Feb", "Mar", "Apr", "May", "Jun",
+		"Jul", "Aug", "Sep", "Oct", "Nov", "Dec"
+	};
+	register int		lead;
+	register int		trail;
+	int DIVISOR = 10;
+
+	/*
+	** The packaged localtime_rz and gmtime_r never put out-of-range
+	** values in tm_wday or tm_mon, but since this code might be compiled
+	** with other (perhaps experimental) versions, paranoia is in order.
+	*/
+	printf("%s %s%3d %.2d:%.2d:%.2d ",
+		((0 <= timeptr->tm_wday
+		  && timeptr->tm_wday < (int)(sizeof wday_name / sizeof wday_name[0]))
+		 ? wday_name[timeptr->tm_wday] : "???"),
+		((0 <= timeptr->tm_mon
+		  && timeptr->tm_mon < (int)(sizeof mon_name / sizeof mon_name[0]))
+		 ? mon_name[timeptr->tm_mon] : "???"),
+		timeptr->tm_mday, timeptr->tm_hour,
+		timeptr->tm_min, timeptr->tm_sec);
+	trail = timeptr->tm_year % DIVISOR + TM_YEAR_BASE % DIVISOR;
+	lead = timeptr->tm_year / DIVISOR + TM_YEAR_BASE / DIVISOR +
+		trail / DIVISOR;
+	trail %= DIVISOR;
+	if (trail < 0 && lead > 0) {
+		trail += DIVISOR;
+		--lead;
+	} else if (lead < 0 && trail > 0) {
+		trail -= DIVISOR;
+		++lead;
+	}
+	if (lead == 0)
+		printf("%d", trail);
+	else	printf("%d%d", lead, ((trail < 0) ? -trail : trail));
+}
diff --git a/contrib/tzcode/zic.8 b/contrib/tzcode/zic.8
new file mode 100644
index 000000000000..79624da4e9e2
--- /dev/null
+++ b/contrib/tzcode/zic.8
@@ -0,0 +1,856 @@
+.\" This file is in the public domain, so clarified as of
+.\" 2009-05-17 by Arthur David Olson.
+.\"
+.\" $FreeBSD$
+.\"
+.Dd December 15, 2022
+.Dt ZIC 8
+.Os
+.Sh NAME
+.Nm zic
+.Nd timezone compiler
+.Sh SYNOPSIS
+.Nm
+.Op Fl -help
+.Op Fl -version
+.Op Fl Dsv
+.Op Fl b Ar slim | fat
+.Op Fl d Ar directory
+.Op Fl g Ar gid
+.Op Fl l Ar localtime
+.Op Fl L Ar leapseconds
+.Op Fl m Ar mode
+.Op Fl p Ar posixrules
+.Oo
+.Fl r
+.Op @ Ns Ar lo Ns
+.Op /@ Ns Ar hi
+.Oc
+.Op Fl R @ Ns Ar hi
+.Op Fl t Ar localtime-link
+.Op Fl u Ar uid
+.Op Ar filename ...
+.Sh DESCRIPTION
+The
+.Nm
+program reads text from the file(s) named on the command line
+and creates the timezone information format (TZif) files
+specified in this input.
+If a
+.Ar filename
+is
+.Dq "-" ,
+standard input is read.
+.Pp
+The following options are available:
+.Bl -tag -width indent
+.It Fl -version
+Output version information and exit.
+.It Fl -help
+Output short usage message and exit.
+.It Fl b Ar bloat
+Output backward-compatibility data as specified by
+.Ar bloat .
+If
+.Ar bloat
+is
+.Cm fat ,
+generate additional data entries that work around potential bugs or
+incompatibilities in older software, such as software that mishandles
+the 64-bit generated data.
+If
+.Ar bloat
+is
+.Cm slim ,
+keep the output files small; this can help check for the bugs
+and incompatibilities.
+The default is
+.Cm slim ,
+as software that mishandles 64-bit data typically
+mishandles timestamps after the year 2038 anyway.
+Also see the
+.Fl r
+option for another way to alter output size.
+.It Fl d Ar directory
+Create time conversion information files in the named directory rather than
+in the standard directory named below.
+.It Fl l Ar timezone
+Use
+.Ar timezone
+as local time.
+The
+.Nm
+utility
+will act as if the input contained a link line of the form
+.Bd -literal -offset indent
+Link	timezone		localtime
+.Ed
+.Pp
+If
+.Ar timezone
+is
+.Ql - ,
+any already-existing link is removed.
+.It Fl L Ar filename
+Read leap second information from the file with the given name.
+If this option is not used,
+no leap second information appears in output files.
+.It Fl p Ar timezone
+Use
+.Ar timezone 's
+rules when handling nonstandard
+TZ strings like
+.Dq "EET\-2EEST"
+that lack transition rules.
+The
+.Nm
+utility
+will act as if the input contained a link line of the form
+.Bd -literal -offset indent
+Link	\fItimezone\fP		posixrules
+.Ed
+.Pp
+This feature is obsolete and poorly supported.
+Among other things it should not be used for timestamps after the year 2037,
+and it should not be combined with
+.Fl b Cm slim
+if
+.Ar timezone 's
+transitions are at standard time or Universal Time (UT) instead of local time.
+.Pp
+If
+.Ar timezone
+is
+.Ql - ,
+any already-existing link is removed.
+.It Fl r Oo @ Ns Ar lo Oc Ns Oo /@ Ns Ar hi Oc
+Limit the applicability of output files
+to timestamps in the range from
+.Ar lo
+(inclusive) to
+.Ar hi
+(exclusive), where
+.Ar lo
+and
+.Ar hi
+are possibly-signed decimal counts of seconds since the Epoch
+(1970-01-01 00:00:00 UTC).
+Omitted counts default to extreme values.
+The output files use UT offset 0 and abbreviation
+.Dq "\-00"
+in place of the omitted timestamp data.
+For example,
+.Fl r @0
+omits data intended for negative timestamps (i.e., before the Epoch), and
+.Fl r @0/@2147483648
+outputs data intended only for nonnegative timestamps that fit into
+31-bit signed integers.
+Although this option typically reduces the output file's size,
+the size can increase due to the need to represent the timestamp range
+boundaries, particularly if
+.Ar hi
+causes a TZif file to contain explicit entries for
+.Em pre-
+.Ar hi
+transitions rather than concisely representing them
+with an extended POSIX TZ string.
+Also see the
+.Fl b Cm slim
+option for another way to shrink output size.
+.It Fl R @ Ns Ar hi
+Generate redundant trailing explicit transitions for timestamps
+that occur less than
+.Ar hi
+seconds since the Epoch, even though the transitions could be
+more concisely represented via the extended POSIX TZ string.
+This option does not affect the represented timestamps.
+Although it accommodates nonstandard TZif readers
+that ignore the extended POSIX TZ string,
+it increases the size of the altered output files.
+.It Fl t Ar file
+When creating local time information, put the configuration link in
+the named file rather than in the standard location.
+.It Fl v
+Be more verbose, and complain about the following situations:
+.Bl -bullet
+.It
+The input specifies a link to a link,
+something not supported by some older parsers, including
+.Nm
+itself through release 2022e.
+.It
+A year that appears in a data file is outside the range
+of representable years.
+.It
+A time of 24:00 or more appears in the input.
+Pre-1998 versions of
+.Nm
+prohibit 24:00, and pre-2007 versions prohibit times greater than 24:00.
+.It
+A rule goes past the start or end of the month.
+Pre-2004 versions of
+.Nm
+prohibit this.
+.It
+A time zone abbreviation uses a
+.Ql %z
+format.
+Pre-2015 versions of
+.Nm
+do not support this.
+.It
+A timestamp contains fractional seconds.
+Pre-2018 versions of
+.Nm
+do not support this.
+.It
+The input contains abbreviations that are mishandled by pre-2018 versions of
+.Nm
+due to a longstanding coding bug.
+These abbreviations include
+.Dq L
+for
+.Dq Link ,
+.Dq mi
+for
+.Dq min ,
+.Dq Sa
+for
+.Dq Sat ,
+and
+.Dq Su
+for
+.Dq Sun .
+.It
+The output file does not contain all the information about the
+long-term future of a timezone, because the future cannot be summarized as
+an extended POSIX TZ string.
+For example, as of 2019 this problem
+occurs for Iran's daylight-saving rules for the predicted future, as
+these rules are based on the Iranian calendar, which cannot be
+represented.
+.It
+The output contains data that may not be handled properly by client
+code designed for older
+.Nm
+output formats.
+These compatibility issues affect only timestamps
+before 1970 or after the start of 2038.
+.It
+The output contains a truncated leap second table,
+which can cause some older TZif readers to misbehave.
+This can occur if the
+.Fl L
+option is used, and either an Expires line is present or
+the
+.Fl r
+option is also used.
+.It
+The output file contains more than 1200 transitions,
+which may be mishandled by some clients.
+The current reference client supports at most 2000 transitions;
+pre-2014 versions of the reference client support at most 1200
+transitions.
+.It
+A time zone abbreviation has fewer than 3 or more than 6 characters.
+POSIX requires at least 3, and requires implementations to support
+at least 6.
+.It
+An output file name contains a byte that is not an ASCII letter,
+.Dq "\-" ,
+.Dq "/" ,
+or
+.Dq "_" ;
+or it contains a file name component that contains more than 14 bytes
+or that starts with
+.Dq "\-" .
+.El
+.El
+.RE
+.Sh FILES
+Input files use the format described in this section; output files use
+.Xr tzfile 5
+format.
+.Pp
+Input files should be text files, that is, they should be a series of
+zero or more lines, each ending in a newline byte and containing at
+most 2048 bytes counting the newline, and without any NUL bytes.
+The input text's encoding
+is typically UTF-8 or ASCII; it should have a unibyte representation
+for the POSIX Portable Character Set (PPCS)
+\*<https://pubs\*:.opengroup\*:.org/\*:onlinepubs/\*:9699919799/\*:basedefs/\*:V1_chap06\*:.html\*>
+and the encoding's non-unibyte characters should consist entirely of
+non-PPCS bytes.
+Non-PPCS characters typically occur only in comments:
+although output file names and time zone abbreviations can contain
+nearly any character, other software will work better if these are
+limited to the restricted syntax described under the
+.Fl v
+option.
+.Pp
+Input lines are made up of fields.
+Fields are separated from one another by one or more white space characters.
+The white space characters are space, form feed, carriage return, newline,
+tab, and vertical tab.
+Leading and trailing white space on input lines is ignored.
+An unquoted sharp character (\(sh) in the input introduces a comment which extends
+to the end of the line the sharp character appears on.
+White space characters and sharp characters may be enclosed in double quotes
+(\(dq) if they're to be used as part of a field.
+Any line that is blank (after comment stripping) is ignored.
+Nonblank lines are expected to be of one of three types:
+rule lines, zone lines, and link lines.
+.Pp
+Names must be in English and are case insensitive.
+They appear in several contexts, and include month and weekday names
+and keywords such as
+.Dq "maximum" ,
+.Dq "only" ,
+.Dq "Rolling" ,
+and
+.Dq "Zone" .
+A name can be abbreviated by omitting all but an initial prefix; any
+abbreviation must be unambiguous in context.
+.Pp
+A rule line has the form
+.Bd -literal -offset indent
+Rule	NAME	FROM	TO	\-	IN	ON	AT	SAVE	LETTER/S
+.Ed
+.Pp
+For example:
+.Bd -literal -offset indent
+Rule	US	1967	1973	\-	Apr	lastSun	2:00w	1:00d	D
+.Ed
+.Pp
+The fields that make up a rule line are:
+.Bl -tag -width "LETTER/S"
+.It NAME
+Gives the name of the rule set that contains this line.
+The name must start with a character that is neither
+an ASCII digit nor
+.Dq \-
+nor
+.Dq + .
+To allow for future extensions,
+an unquoted name should not contain characters from the set
+.Dq Ql "!$%&'()*,/:;<=>?@[\]^`{|}~" .
+.It FROM
+Gives the first year in which the rule applies.
+Any signed integer year can be supplied; the proleptic Gregorian calendar
+is assumed, with year 0 preceding year 1.
+The word
+.Cm minimum
+(or an abbreviation) means the indefinite past.
+The word
+.Cm maximum
+(or an abbreviation) means the indefinite future.
+Rules can describe times that are not representable as time values,
+with the unrepresentable times ignored; this allows rules to be portable
+among hosts with differing time value types.
+.It TO
+Gives the final year in which the rule applies.
+In addition to
+.Cm minimum
+and
+.Cm maximum
+(as above),
+the word
+.Cm only
+(or an abbreviation)
+may be used to repeat the value of the
+.Ar FROM
+field.
+.It \-
+Is a reserved field and should always contain
+.Ql \-
+for compatibility with older versions of
+.Nm .
+It was previously known as the
+.Ar TYPE
+field, which could contain values to allow a
+separate script to further restrict in which
+.Dq types
+of years the rule would apply.
+.It IN
+Names the month in which the rule takes effect.
+Month names may be abbreviated.
+.It ON
+Gives the day on which the rule takes effect.
+Recognized forms include:
+.Bl -tag -compact -width "Sun<=25"
+.It 5
+the fifth of the month
+.It lastSun
+the last Sunday in the month
+.It lastMon
+the last Monday in the month
+.It Sun>=8
+first Sunday on or after the eighth
+.It Sun<=25
+last Sunday on or before the 25th
+.El
+.Pp
+A weekday name (e.g.,
+.Ql "Sunday" )
+or a weekday name preceded by
+.Dq "last"
+(e.g.,
+.Ql "lastSunday" )
+may be abbreviated or spelled out in full.
+There must be no white space characters within the
+.Ar ON
+field.
+The
+.Dq <=
+and
+.Dq >=
+constructs can result in a day in the neighboring month;
+for example, the IN-ON combination
+.Dq "Oct Sun>=31"
+stands for the first Sunday on or after October 31,
+even if that Sunday occurs in November.
+.It AT
+Gives the time of day at which the rule takes effect,
+relative to 00:00, the start of a calendar day.
+Recognized forms include:
+.Bl -tag -compact -width "00:19:32.13"
+.It 2
+time in hours
+.It 2:00
+time in hours and minutes
+.It 01:28:14
+time in hours, minutes, and seconds
+.It 00:19:32.13
+time with fractional seconds
+.It 12:00
+midday, 12 hours after 00:00
+.It 15:00
+3 PM, 15 hours after 00:00
+.It 24:00
+end of day, 24 hours after 00:00
+.It 260:00
+260 hours after 00:00
+.It \-2:30
+2.5 hours before 00:00
+.It \-
+equivalent to 0
+.El
+.Pp
+Although
+.Nm
+rounds times to the nearest integer second
+(breaking ties to the even integer), the fractions may be useful
+to other applications requiring greater precision.
+The source format does not specify any maximum precision.
+Any of these forms may be followed by the letter
+.Ql w
+if the given time is local or
+.Dq "wall clock"
+time,
+.Ql s
+if the given time is standard time without any adjustment for daylight saving,
+or
+.Ql u
+(or
+.Ql g
+or
+.Ql z )
+if the given time is universal time;
+in the absence of an indicator,
+local (wall clock) time is assumed.
+These forms ignore leap seconds; for example,
+if a leap second occurs at 00:59:60 local time,
+.Ql "1:00"
+stands for 3601 seconds after local midnight instead of the usual 3600 seconds.
+The intent is that a rule line describes the instants when a
+clock/calendar set to the type of time specified in the
+.Ar AT
+field would show the specified date and time of day.
+.It SAVE
+Gives the amount of time to be added to local standard time when the rule is in
+effect, and whether the resulting time is standard or daylight saving.
+This field has the same format as the
+.Ar AT
+field
+except with a different set of suffix letters:
+.Ql s
+for standard time and
+.Ql d
+for daylight saving time.
+The suffix letter is typically omitted, and defaults to
+.Ql s
+if the offset is zero and to
+.Ql d
+otherwise.
+Negative offsets are allowed; in Ireland, for example, daylight saving
+time is observed in winter and has a negative offset relative to
+Irish Standard Time.
+The offset is merely added to standard time; for example,
+.Nm
+does not distinguish a 10:30 standard time plus an 0:30
+.Ar SAVE
+from a 10:00 standard time plus a 1:00
+.Ar SAVE .
+.It LETTER/S
+Gives the
+.Dq "variable part"
+(for example, the
+.Dq "S"
+or
+.Dq "D"
+in
+.Dq "EST"
+or
+.Dq "EDT" )
+of time zone abbreviations to be used when this rule is in effect.
+If this field is
+.Ql \- ,
+the variable part is null.
+.El
+.Pp
+A zone line has the form
+.Bd -literal -offset indent
+Zone	NAME	STDOFF	RULES	FORMAT	[UNTIL]
+.Ed
+.Pp
+For example:
+.Bd -literal -offset indent
+Zone	Asia/Amman	2:00	Jordan	EE%sT	2017 Oct 27 01:00
+.Ed
+.Pp
+The fields that make up a zone line are:
+.Bl -tag -width "STDOFF"
+.It NAME
+The name of the timezone.
+This is the name used in creating the time conversion information file for the
+timezone.
+It should not contain a file name component
+.Dq ".\&"
+or
+.Dq ".." ;
+a file name component is a maximal substring that does not contain
+.Dq "/" .
+.It STDOFF
+The amount of time to add to UT to get standard time,
+without any adjustment for daylight saving.
+This field has the same format as the
+.Ar AT
+and
+.Ar SAVE
+fields of rule lines, except without suffix letters;
+begin the field with a minus sign if time must be subtracted from UT.
+.It RULES
+The name of the rules that apply in the timezone or,
+alternatively, a field in the same format as a rule-line SAVE column,
+giving the amount of time to be added to local standard time
+and whether the resulting time is standard or daylight saving.
+If this field is
+.Ql \-
+then standard time always applies.
+When an amount of time is given, only the sum of standard time and
+this amount matters.
+.It FORMAT
+The format for time zone abbreviations.
+The pair of characters
+.Ql %s
+is used to show where the
+.Dq "variable part"
+of the time zone abbreviation goes.
+Alternatively, a format can use the pair of characters
+.Ql %z
+to stand for the UT offset in the form
+.Ar \(+- hh ,
+.Ar \(+- hhmm ,
+or
+.Ar \(+- hhmmss ,
+using the shortest form that does not lose information, where
+.Ar hh ,
+.Ar mm ,
+and
+.Ar ss
+are the hours, minutes, and seconds east (+) or west (\-) of UT.
+Alternatively,
+a slash (/)
+separates standard and daylight abbreviations.
+To conform to POSIX, a time zone abbreviation should contain only
+alphanumeric ASCII characters,
+.Ql "+"
+and
+.Ql "\-".
+By convention, the time zone abbreviation
+.Ql "\-00"
+is a placeholder that means local time is unspecified.
+.It UNTIL
+The time at which the UT offset or the rule(s) change for a location.
+It takes the form of one to four fields
+.Ar YEAR Op Ar MONTH Op Ar DAY Op Ar TIME .
+If this is specified,
+the time zone information is generated from the given UT offset
+and rule change until the time specified, which is interpreted using
+the rules in effect just before the transition.
+The month, day, and time of day have the same format as the
+.Ar IN ,
+.Ar ON ,
+and
+.Ar AT
+fields of a rule; trailing fields can be omitted, and default to the
+earliest possible value for the missing fields.
+.IP
+The next line must be a
+.Dq "continuation"
+line; this has the same form as a zone line except that the
+string
+.Dq "Zone"
+and the name are omitted, as the continuation line will
+place information starting at the time specified as the
+.Dq "until"
+information in the previous line in the file used by the previous line.
+Continuation lines may contain
+.Dq "until"
+information, just as zone lines do, indicating that the next line is a further
+continuation.
+.El
+.Pp
+If a zone changes at the same instant that a rule would otherwise take
+effect in the earlier zone or continuation line, the rule is ignored.
+A zone or continuation line
+.Ar L
+with a named rule set starts with standard time by default:
+that is, any of
+.Ar L 's
+timestamps preceding
+.Ar L 's
+earliest rule use the rule in effect after
+.Ar L 's
+first transition into standard time.
+In a single zone it is an error if two rules take effect at the same
+instant, or if two zone changes take effect at the same instant.
+.Pp
+If a continuation line subtracts
+.Ar N
+seconds from the UT offset after a transition that would be
+interpreted to be later if using the continuation line's UT offset and
+rules, the
+.Dq "until"
+time of the previous zone or continuation line is interpreted
+according to the continuation line's UT offset and rules, and any rule
+that would otherwise take effect in the next
+.Ar N
+seconds is instead assumed to take effect simultaneously.
+For example:
+.Bd -literal -offset indent
+# Rule	NAME	FROM	TO	\*-	IN	ON	AT	SAVE	LETTER/S
+Rule	US	1967	2006	-	Oct	lastSun	2:00	0	S
+Rule	US	1967	1973	-	Apr	lastSun	2:00	1:00	D
+
+# Zone\0\0NAME	STDOFF	RULES	FORMAT	[UNTIL]
+Zone\0\0America/Menominee	\*-5:00	\*-	EST	1973 Apr 29 2:00
+	\*-6:00	US	C%sT
+.Ed
+Here, an incorrect reading would be there were two clock changes on 1973-04-29,
+the first from 02:00 EST (\-05) to 01:00 CST (\-06),
+and the second an hour later from 02:00 CST (\-06) to 03:00 CDT (\-05).
+However,
+.Nm
+interprets this more sensibly as a single transition from 02:00 CST (\-05) to
+02:00 CDT (\-05).
+.Pp
+A link line has the form
+.Bd -literal -offset indent
+Link	TARGET	LINK-NAME
+.Ed
+.Pp
+For example:
+.Bd -literal -offset indent
+Link	Europe/Istanbul	Asia/Istanbul
+.Ed
+.Pp
+The
+.Ar TARGET
+field should appear as the
+.Ar NAME
+field in some zone line or as the
+.Ar LINK-NAME
+field in some link line.
+The
+.Ar LINK-NAME
+field is used as an alternative name for that zone;
+it has the same syntax as a zone line's
+.Ar NAME
+field.
+Links can chain together, although the behavior is unspecified if a
+chain of one or more links does not terminate in a Zone name.
+A link line can appear before the line that defines the link target.
+For example:
+.Bd -literal -offset indent
+Link	Greenwich	G_M_T
+Link	Etc/GMT	Greenwich
+Zone	Etc/GMT\0\00\0\0\-\0\0GMT
+.Ed
+.Pp
+The two links are chained together, and G_M_T, Greenwich, and Etc/GMT
+all name the same zone.
+.Pp
+Except for continuation lines,
+lines may appear in any order in the input.
+However, the behavior is unspecified if multiple zone or link lines
+define the same name.
+.Pp
+The file that describes leap seconds can have leap lines and an
+expiration line.
+Leap lines have the following form:
+.Bd -literal -offset indent
+Leap	YEAR	MONTH	DAY	HH:MM:SS	CORR	R/S
+.Ed
+.Pp
+For example:
+.Bd -literal -offset indent
+Leap	2016	Dec	31	23:59:60	+	S
+.Ed
+.Pp
+The
+.Ar YEAR ,
+.Ar MONTH ,
+.Ar DAY ,
+and
+.Ar HH:MM:SS
+fields tell when the leap second happened.
+The
+.Ar CORR
+field
+should be
+.Ql "+"
+if a second was added
+or
+.Ql "\-"
+if a second was skipped.
+The
+.Ar R/S
+field
+should be (an abbreviation of)
+.Dq "Stationary"
+if the leap second time given by the other fields should be interpreted as UTC
+or
+(an abbreviation of)
+.Dq "Rolling"
+if the leap second time given by the other fields should be interpreted as
+local (wall clock) time.
+.Pp
+Rolling leap seconds were implemented back when it was not
+clear whether common practice was rolling or stationary,
+with concerns that one would see
+Times Square ball drops where there'd be a
+.Dq "3... 2... 1... leap... Happy New Year"
+countdown, placing the leap second at
+midnight New York time rather than midnight UTC.
+However, this countdown style does not seem to have caught on,
+which means rolling leap seconds are not used in practice;
+also, they are not supported if the
+.Fl r
+option is used.
+.Pp
+The expiration line, if present, has the form:
+.Bd -literal -offset indent
+Expires	YEAR	MONTH	DAY	HH:MM:SS
+.Ed
+.Pp
+For example:
+.Bd -literal -offset indent
+Expires	2020	Dec	28	00:00:00
+.Ed
+.Pp
+The
+.Ar YEAR ,
+.Ar MONTH ,
+.Ar DAY ,
+and
+.Ar HH:MM:SS
+fields give the expiration timestamp in UTC for the leap second table.
+.Sh "EXTENDED EXAMPLE"
+Here is an extended example of
+.Nm
+input, intended to illustrate many of its features.
+.Bd -literal -offset indent
+# Rule	NAME	FROM	TO	\-	IN	ON	AT	SAVE	LETTER/S
+Rule	Swiss	1941	1942	\-	May	Mon>=1	1:00	1:00	S
+Rule	Swiss	1941	1942	\-	Oct	Mon>=1	2:00	0	\-
+
+Rule	EU	1977	1980	\-	Apr	Sun>=1	1:00u	1:00	S
+Rule	EU	1977	only	\-	Sep	lastSun	1:00u	0	\-
+Rule	EU	1978	only	\-	Oct	 1	1:00u	0	\-
+Rule	EU	1979	1995	\-	Sep	lastSun	1:00u	0	\-
+Rule	EU	1981	max	\-	Mar	lastSun	1:00u	1:00	S
+Rule	EU	1996	max	\-	Oct	lastSun	1:00u	0	\-
+
+# Zone	NAME	STDOFF	RULES	FORMAT	[UNTIL]
+Zone	Europe/Zurich	0:34:08	\-	LMT	1853 Jul 16
+		0:29:45.50	\-	BMT	1894 Jun
+		1:00	Swiss	CE%sT	1981
+		1:00	EU	CE%sT
+
+Link	Europe/Zurich	Europe/Vaduz
+.Ed
+.Pp
+In this example, the EU rules are for the European Union
+and for its predecessor organization, the European Communities.
+The timezone is named Europe/Zurich and it has the alias Europe/Vaduz.
+This example says that Zurich was 34 minutes and 8
+seconds east of UT until 1853-07-16 at 00:00, when the legal offset
+was changed to
+7\(de26\(fm22.50\(sd,
+which works out to 0:29:45.50;
+.Nm
+treats this by rounding it to 0:29:46.
+After 1894-06-01 at 00:00 the UT offset became one hour
+and Swiss daylight saving rules (defined with lines beginning with
+.Dq "Rule Swiss")
+apply.
+From 1981 to the present, EU daylight saving rules have
+applied, and the UTC offset has remained at one hour.
+.Pp
+In 1941 and 1942, daylight saving time applied from the first Monday
+in May at 01:00 to the first Monday in October at 02:00.
+The pre-1981 EU daylight-saving rules have no effect
+here, but are included for completeness.
+Since 1981, daylight
+saving has begun on the last Sunday in March at 01:00 UTC.
+Until 1995 it ended the last Sunday in September at 01:00 UTC,
+but this changed to the last Sunday in October starting in 1996.
+.Pp
+For purposes of display,
+.Dq "LMT"
+and
+.Dq "BMT"
+were initially used, respectively.
+Since
+Swiss rules and later EU rules were applied, the time zone abbreviation
+has been CET for standard time and CEST for daylight saving
+time.
+.Sh FILES
+.Bl -tag -width "/usr/share/zoneinfo"
+.It Pa /etc/localtime
+Default local timezone file.
+.It Pa /usr/share/zoneinfo
+Default timezone information directory.
+.El
+.Sh NOTES
+For areas with more than two types of local time,
+you may need to use local standard time in the
+.Ar AT
+field of the earliest transition time's rule to ensure that
+the earliest transition time recorded in the compiled file is correct.
+.Pp
+If,
+for a particular timezone,
+a clock advance caused by the start of daylight saving
+coincides with and is equal to
+a clock retreat caused by a change in UT offset,
+.Nm
+produces a single transition to daylight saving at the new UT offset
+without any change in local (wall clock) time.
+To get separate transitions
+use multiple zone continuation lines
+specifying transition instants using universal time.
+.Sh SEE ALSO
+.Xr tzfile 5 ,
+.Xr zdump 8
diff --git a/contrib/tzcode/zic.c b/contrib/tzcode/zic.c
new file mode 100644
index 000000000000..3be46c8563d7
--- /dev/null
+++ b/contrib/tzcode/zic.c
@@ -0,0 +1,4051 @@
+/* Compile .zi time zone data into TZif binary files.  */
+
+/*
+** This file is in the public domain, so clarified as of
+** 2006-07-17 by Arthur David Olson.
+*/
+
+/* Use the system 'time' function, instead of any private replacement.
+   This avoids creating an unnecessary dependency on localtime.c.  */
+#undef EPOCH_LOCAL
+#undef EPOCH_OFFSET
+#undef RESERVE_STD_EXT_IDS
+#undef time_tz
+
+#include "version.h"
+#include "private.h"
+#include "tzfile.h"
+
+#include <fcntl.h>
+#include <locale.h>
+#include <signal.h>
+#include <stdarg.h>
+#include <stdio.h>
+
+typedef int_fast64_t	zic_t;
+static zic_t const
+  ZIC_MIN = INT_FAST64_MIN,
+  ZIC_MAX = INT_FAST64_MAX,
+  ZIC32_MIN = -1 - (zic_t) 0x7fffffff,
+  ZIC32_MAX = 0x7fffffff;
+#define SCNdZIC SCNdFAST64
+
+#ifndef ZIC_MAX_ABBR_LEN_WO_WARN
+# define ZIC_MAX_ABBR_LEN_WO_WARN 6
+#endif /* !defined ZIC_MAX_ABBR_LEN_WO_WARN */
+
+/* An upper bound on how much a format might grow due to concatenation.  */
+enum { FORMAT_LEN_GROWTH_BOUND = 5 };
+
+#ifdef HAVE_DIRECT_H
+# include <direct.h>
+# include <io.h>
+# undef mkdir
+# define mkdir(name, mode) _mkdir(name)
+#endif
+
+#ifndef HAVE_GETRANDOM
+# ifdef __has_include
+#  if __has_include(<sys/random.h>)
+#   include <sys/random.h>
+#  endif
+# elif 2 < __GLIBC__ + (25 <= __GLIBC_MINOR__)
+#  include <sys/random.h>
+# endif
+# define HAVE_GETRANDOM GRND_RANDOM
+#elif HAVE_GETRANDOM
+# include <sys/random.h>
+#endif
+
+#if HAVE_SYS_STAT_H
+# include <sys/stat.h>
+#endif
+#ifdef S_IRUSR
+# define MKDIR_UMASK (S_IRUSR|S_IWUSR|S_IXUSR|S_IRGRP|S_IXGRP|S_IROTH|S_IXOTH)
+#else
+# define MKDIR_UMASK 0755
+#endif
+
+/* The minimum alignment of a type, for pre-C23 platforms.  */
+#if __STDC_VERSION__ < 201112
+# define alignof(type) offsetof(struct { char a; type b; }, b)
+#elif __STDC_VERSION__ < 202311
+# include <stdalign.h>
+#endif
+
+/* The maximum length of a text line, including the trailing newline.  */
+#ifndef _POSIX2_LINE_MAX
+# define _POSIX2_LINE_MAX 2048
+#endif
+
+/* The type for line numbers.  Use PRIdMAX to format them; formerly
+   there was also "#define PRIdLINENO PRIdMAX" and formats used
+   PRIdLINENO, but xgettext cannot grok that.  */
+typedef intmax_t lineno;
+
+struct rule {
+	int		r_filenum;
+	lineno		r_linenum;
+	const char *	r_name;
+
+	zic_t		r_loyear;	/* for example, 1986 */
+	zic_t		r_hiyear;	/* for example, 1986 */
+	bool		r_lowasnum;
+	bool		r_hiwasnum;
+
+	int		r_month;	/* 0..11 */
+
+	int		r_dycode;	/* see below */
+	int		r_dayofmonth;
+	int		r_wday;
+
+	zic_t		r_tod;		/* time from midnight */
+	bool		r_todisstd;	/* is r_tod standard time? */
+	bool		r_todisut;	/* is r_tod UT? */
+	bool		r_isdst;	/* is this daylight saving time? */
+	zic_t		r_save;		/* offset from standard time */
+	const char *	r_abbrvar;	/* variable part of abbreviation */
+
+	bool		r_todo;		/* a rule to do (used in outzone) */
+	zic_t		r_temp;		/* used in outzone */
+};
+
+/*
+** r_dycode	r_dayofmonth	r_wday
+*/
+enum {
+  DC_DOM,	/* 1..31 */	/* unused */
+  DC_DOWGEQ,	/* 1..31 */	/* 0..6 (Sun..Sat) */
+  DC_DOWLEQ	/* 1..31 */	/* 0..6 (Sun..Sat) */
+};
+
+struct zone {
+	int		z_filenum;
+	lineno		z_linenum;
+
+	const char *	z_name;
+	zic_t		z_stdoff;
+	char *		z_rule;
+	const char *	z_format;
+	char		z_format_specifier;
+
+	bool		z_isdst;
+	zic_t		z_save;
+
+	struct rule *	z_rules;
+	ptrdiff_t	z_nrules;
+
+	struct rule	z_untilrule;
+	zic_t		z_untiltime;
+};
+
+#if !HAVE_POSIX_DECLS
+extern int	getopt(int argc, char * const argv[],
+			const char * options);
+extern int	link(const char * target, const char * linkname);
+extern char *	optarg;
+extern int	optind;
+#endif
+
+#if ! HAVE_SYMLINK
+static ssize_t
+readlink(char const *restrict file, char *restrict buf, size_t size)
+{
+  errno = ENOTSUP;
+  return -1;
+}
+static int
+symlink(char const *target, char const *linkname)
+{
+  errno = ENOTSUP;
+  return -1;
+}
+#endif
+#ifndef AT_SYMLINK_FOLLOW
+# if HAVE_LINK
+#  define linkat(targetdir, target, linknamedir, linkname, flag) \
+     (itssymlink(target) ? (errno = ENOTSUP, -1) : link(target, linkname))
+# else
+#  define linkat(targetdir, target, linknamedir, linkname, flag) \
+     (errno = ENOTSUP, -1)
+# endif
+#endif
+
+static void	addtt(zic_t starttime, int type);
+static int	addtype(zic_t, char const *, bool, bool, bool);
+static void	leapadd(zic_t, int, int);
+static void	adjleap(void);
+static void	associate(void);
+static void	dolink(const char *, const char *, bool);
+static int	getfields(char *, char **, int);
+static zic_t	gethms(const char * string, const char * errstring);
+static zic_t	getsave(char *, bool *);
+static void	inexpires(char **, int);
+static void	infile(int, char const *);
+static void	inleap(char ** fields, int nfields);
+static void	inlink(char ** fields, int nfields);
+static void	inrule(char ** fields, int nfields);
+static bool	inzcont(char ** fields, int nfields);
+static bool	inzone(char ** fields, int nfields);
+static bool	inzsub(char **, int, bool);
+static bool	itssymlink(char const *);
+static bool	is_alpha(char a);
+static char	lowerit(char);
+static void	mkdirs(char const *, bool);
+static void	newabbr(const char * abbr);
+static zic_t	oadd(zic_t t1, zic_t t2);
+static void	outzone(const struct zone * zp, ptrdiff_t ntzones);
+static zic_t	rpytime(const struct rule * rp, zic_t wantedy);
+static bool	rulesub(struct rule * rp,
+			const char * loyearp, const char * hiyearp,
+			const char * typep, const char * monthp,
+			const char * dayp, const char * timep);
+static void	setgroup(gid_t *flag, const char *name);
+static void	setuser(uid_t *flag, const char *name);
+static zic_t	tadd(zic_t t1, zic_t t2);
+
+/* Bound on length of what %z can expand to.  */
+enum { PERCENT_Z_LEN_BOUND = sizeof "+995959" - 1 };
+
+static int		charcnt;
+static bool		errors;
+static bool		warnings;
+static int		filenum;
+static int		leapcnt;
+static bool		leapseen;
+static zic_t		leapminyear;
+static zic_t		leapmaxyear;
+static lineno		linenum;
+static size_t		max_abbrvar_len = PERCENT_Z_LEN_BOUND;
+static int		max_format_len;
+static zic_t		max_year;
+static zic_t		min_year;
+static bool		noise;
+static int		rfilenum;
+static lineno		rlinenum;
+static const char *	progname;
+static char const *	leapsec;
+static char *const *	main_argv;
+static ptrdiff_t	timecnt;
+static ptrdiff_t	timecnt_alloc;
+static int		typecnt;
+static int		unspecifiedtype;
+
+/*
+** Line codes.
+*/
+
+enum {
+  LC_RULE,
+  LC_ZONE,
+  LC_LINK,
+  LC_LEAP,
+  LC_EXPIRES
+};
+
+/*
+** Which fields are which on a Zone line.
+*/
+
+enum {
+  ZF_NAME = 1,
+  ZF_STDOFF,
+  ZF_RULE,
+  ZF_FORMAT,
+  ZF_TILYEAR,
+  ZF_TILMONTH,
+  ZF_TILDAY,
+  ZF_TILTIME,
+  ZONE_MAXFIELDS,
+  ZONE_MINFIELDS = ZF_TILYEAR
+};
+
+/*
+** Which fields are which on a Zone continuation line.
+*/
+
+enum {
+  ZFC_STDOFF,
+  ZFC_RULE,
+  ZFC_FORMAT,
+  ZFC_TILYEAR,
+  ZFC_TILMONTH,
+  ZFC_TILDAY,
+  ZFC_TILTIME,
+  ZONEC_MAXFIELDS,
+  ZONEC_MINFIELDS = ZFC_TILYEAR
+};
+
+/*
+** Which files are which on a Rule line.
+*/
+
+enum {
+  RF_NAME = 1,
+  RF_LOYEAR,
+  RF_HIYEAR,
+  RF_COMMAND,
+  RF_MONTH,
+  RF_DAY,
+  RF_TOD,
+  RF_SAVE,
+  RF_ABBRVAR,
+  RULE_FIELDS
+};
+
+/*
+** Which fields are which on a Link line.
+*/
+
+enum {
+  LF_TARGET = 1,
+  LF_LINKNAME,
+  LINK_FIELDS
+};
+
+/*
+** Which fields are which on a Leap line.
+*/
+
+enum {
+  LP_YEAR = 1,
+  LP_MONTH,
+  LP_DAY,
+  LP_TIME,
+  LP_CORR,
+  LP_ROLL,
+  LEAP_FIELDS,
+
+  /* Expires lines are like Leap lines, except without CORR and ROLL fields.  */
+  EXPIRES_FIELDS = LP_TIME + 1
+};
+
+/* The maximum number of fields on any of the above lines.
+   (The "+"s pacify gcc -Wenum-compare.)  */
+enum {
+  MAX_FIELDS = max(max(+RULE_FIELDS, +LINK_FIELDS),
+		   max(+LEAP_FIELDS, +EXPIRES_FIELDS))
+};
+
+/*
+** Year synonyms.
+*/
+
+enum {
+  YR_MINIMUM,
+  YR_MAXIMUM,
+  YR_ONLY
+};
+
+static struct rule *	rules;
+static ptrdiff_t	nrules;	/* number of rules */
+static ptrdiff_t	nrules_alloc;
+
+static struct zone *	zones;
+static ptrdiff_t	nzones;	/* number of zones */
+static ptrdiff_t	nzones_alloc;
+
+struct link {
+	int		l_filenum;
+	lineno		l_linenum;
+	const char *	l_target;
+	const char *	l_linkname;
+};
+
+static struct link *	links;
+static ptrdiff_t	nlinks;
+static ptrdiff_t	nlinks_alloc;
+
+struct lookup {
+	const char *	l_word;
+	const int	l_value;
+};
+
+static struct lookup const *	byword(const char * string,
+					const struct lookup * lp);
+
+static struct lookup const zi_line_codes[] = {
+	{ "Rule",	LC_RULE },
+	{ "Zone",	LC_ZONE },
+	{ "Link",	LC_LINK },
+	{ NULL,		0 }
+};
+static struct lookup const leap_line_codes[] = {
+	{ "Leap",	LC_LEAP },
+	{ "Expires",	LC_EXPIRES },
+	{ NULL,		0}
+};
+
+static struct lookup const	mon_names[] = {
+	{ "January",	TM_JANUARY },
+	{ "February",	TM_FEBRUARY },
+	{ "March",	TM_MARCH },
+	{ "April",	TM_APRIL },
+	{ "May",	TM_MAY },
+	{ "June",	TM_JUNE },
+	{ "July",	TM_JULY },
+	{ "August",	TM_AUGUST },
+	{ "September",	TM_SEPTEMBER },
+	{ "October",	TM_OCTOBER },
+	{ "November",	TM_NOVEMBER },
+	{ "December",	TM_DECEMBER },
+	{ NULL,		0 }
+};
+
+static struct lookup const	wday_names[] = {
+	{ "Sunday",	TM_SUNDAY },
+	{ "Monday",	TM_MONDAY },
+	{ "Tuesday",	TM_TUESDAY },
+	{ "Wednesday",	TM_WEDNESDAY },
+	{ "Thursday",	TM_THURSDAY },
+	{ "Friday",	TM_FRIDAY },
+	{ "Saturday",	TM_SATURDAY },
+	{ NULL,		0 }
+};
+
+static struct lookup const	lasts[] = {
+	{ "last-Sunday",	TM_SUNDAY },
+	{ "last-Monday",	TM_MONDAY },
+	{ "last-Tuesday",	TM_TUESDAY },
+	{ "last-Wednesday",	TM_WEDNESDAY },
+	{ "last-Thursday",	TM_THURSDAY },
+	{ "last-Friday",	TM_FRIDAY },
+	{ "last-Saturday",	TM_SATURDAY },
+	{ NULL,			0 }
+};
+
+static struct lookup const	begin_years[] = {
+	{ "minimum",	YR_MINIMUM },
+	{ "maximum",	YR_MAXIMUM },
+	{ NULL,		0 }
+};
+
+static struct lookup const	end_years[] = {
+	{ "minimum",	YR_MINIMUM },
+	{ "maximum",	YR_MAXIMUM },
+	{ "only",	YR_ONLY },
+	{ NULL,		0 }
+};
+
+static struct lookup const	leap_types[] = {
+	{ "Rolling",	true },
+	{ "Stationary",	false },
+	{ NULL,		0 }
+};
+
+static const int	len_months[2][MONSPERYEAR] = {
+	{ 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 },
+	{ 31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 }
+};
+
+static const int	len_years[2] = {
+	DAYSPERNYEAR, DAYSPERLYEAR
+};
+
+static struct attype {
+	zic_t		at;
+	bool		dontmerge;
+	unsigned char	type;
+} *			attypes;
+static zic_t		utoffs[TZ_MAX_TYPES];
+static char		isdsts[TZ_MAX_TYPES];
+static unsigned char	desigidx[TZ_MAX_TYPES];
+static bool		ttisstds[TZ_MAX_TYPES];
+static bool		ttisuts[TZ_MAX_TYPES];
+static char		chars[TZ_MAX_CHARS];
+static zic_t		trans[TZ_MAX_LEAPS];
+static zic_t		corr[TZ_MAX_LEAPS];
+static char		roll[TZ_MAX_LEAPS];
+
+/*
+** Memory allocation.
+*/
+
+static ATTRIBUTE_NORETURN void
+memory_exhausted(const char *msg)
+{
+	fprintf(stderr, _("%s: Memory exhausted: %s\n"), progname, msg);
+	exit(EXIT_FAILURE);
+}
+
+static ATTRIBUTE_NORETURN void
+size_overflow(void)
+{
+  memory_exhausted(_("size overflow"));
+}
+
+static ATTRIBUTE_REPRODUCIBLE ptrdiff_t
+size_sum(size_t a, size_t b)
+{
+#ifdef ckd_add
+  ptrdiff_t sum;
+  if (!ckd_add(&sum, a, b) /* && sum <= SIZE_MAX */)
+    return sum;
+#else
+  ptrdiff_t sum_max = min(PTRDIFF_MAX, SIZE_MAX);
+  if (a <= sum_max && b <= sum_max - a)
+    return a + b;
+#endif
+  size_overflow();
+}
+
+static ATTRIBUTE_REPRODUCIBLE ptrdiff_t
+size_product(ptrdiff_t nitems, ptrdiff_t itemsize)
+{
+#ifdef ckd_mul
+  ptrdiff_t product;
+  if (!ckd_mul(&product, nitems, itemsize) /* && product <= SIZE_MAX */)
+    return product;
+#else
+  ptrdiff_t nitems_max = min(PTRDIFF_MAX, SIZE_MAX) / itemsize;
+  if (nitems <= nitems_max)
+    return nitems * itemsize;
+#endif
+  size_overflow();
+}
+
+static ATTRIBUTE_REPRODUCIBLE ptrdiff_t
+align_to(ptrdiff_t size, ptrdiff_t alignment)
+{
+  ptrdiff_t lo_bits = alignment - 1, sum = size_sum(size, lo_bits);
+  return sum & ~lo_bits;
+}
+
+#if !HAVE_STRDUP
+static char *
+strdup(char const *str)
+{
+  char *result = malloc(strlen(str) + 1);
+  return result ? strcpy(result, str) : result;
+}
+#endif
+
+static void *
+memcheck(void *ptr)
+{
+	if (ptr == NULL)
+	  memory_exhausted(strerror(HAVE_MALLOC_ERRNO ? errno : ENOMEM));
+	return ptr;
+}
+
+static void * ATTRIBUTE_MALLOC
+emalloc(size_t size)
+{
+  return memcheck(malloc(size));
+}
+
+static void *
+erealloc(void *ptr, size_t size)
+{
+  return memcheck(realloc(ptr, size));
+}
+
+static char * ATTRIBUTE_MALLOC
+estrdup(char const *str)
+{
+  return memcheck(strdup(str));
+}
+
+static ptrdiff_t
+grow_nitems_alloc(ptrdiff_t *nitems_alloc, ptrdiff_t itemsize)
+{
+  ptrdiff_t addend = (*nitems_alloc >> 1) + 1;
+#if defined ckd_add && defined ckd_mul
+  ptrdiff_t product;
+  if (!ckd_add(nitems_alloc, *nitems_alloc, addend)
+      && !ckd_mul(&product, *nitems_alloc, itemsize) /* && product <= SIZE_MAX */)
+    return product;
+#else
+  ptrdiff_t amax = min(PTRDIFF_MAX, SIZE_MAX);
+  if (*nitems_alloc <= ((amax - 1) / 3 * 2) / itemsize) {
+    *nitems_alloc += addend;
+    return *nitems_alloc * itemsize;
+  }
+#endif
+  memory_exhausted(_("integer overflow"));
+}
+
+static void *
+growalloc(void *ptr, ptrdiff_t itemsize, ptrdiff_t nitems,
+	  ptrdiff_t *nitems_alloc)
+{
+  return (nitems < *nitems_alloc
+	  ? ptr
+	  : erealloc(ptr, grow_nitems_alloc(nitems_alloc, itemsize)));
+}
+
+/*
+** Error handling.
+*/
+
+/* In most of the code, an input file name is represented by its index
+   into the main argument vector, except that LEAPSEC_FILENUM stands
+   for leapsec and COMMAND_LINE_FILENUM stands for the command line.  */
+enum { LEAPSEC_FILENUM = -2, COMMAND_LINE_FILENUM = -1 };
+
+/* Return the name of the Ith input file, for diagnostics.  */
+static char const *
+filename(int i)
+{
+  if (i == COMMAND_LINE_FILENUM)
+    return _("command line");
+  else {
+    char const *fname = i == LEAPSEC_FILENUM ? leapsec : main_argv[i];
+    return strcmp(fname, "-") == 0 ? _("standard input") : fname;
+  }
+}
+
+static void
+eats(int fnum, lineno num, int rfnum, lineno rnum)
+{
+	filenum = fnum;
+	linenum = num;
+	rfilenum = rfnum;
+	rlinenum = rnum;
+}
+
+static void
+eat(int fnum, lineno num)
+{
+	eats(fnum, num, 0, -1);
+}
+
+static void ATTRIBUTE_FORMAT((printf, 1, 0))
+verror(const char *const string, va_list args)
+{
+	/*
+	** Match the format of "cc" to allow sh users to
+	**	zic ... 2>&1 | error -t "*" -v
+	** on BSD systems.
+	*/
+	if (filenum)
+	  fprintf(stderr, _("\"%s\", line %"PRIdMAX": "),
+		  filename(filenum), linenum);
+	vfprintf(stderr, string, args);
+	if (rfilenum)
+		fprintf(stderr, _(" (rule from \"%s\", line %"PRIdMAX")"),
+			filename(rfilenum), rlinenum);
+	fprintf(stderr, "\n");
+}
+
+static void ATTRIBUTE_FORMAT((printf, 1, 2))
+error(const char *const string, ...)
+{
+	va_list args;
+	va_start(args, string);
+	verror(string, args);
+	va_end(args);
+	errors = true;
+}
+
+static void ATTRIBUTE_FORMAT((printf, 1, 2))
+warning(const char *const string, ...)
+{
+	va_list args;
+	fprintf(stderr, _("warning: "));
+	va_start(args, string);
+	verror(string, args);
+	va_end(args);
+	warnings = true;
+}
+
+/* Close STREAM.  If it had an I/O error, report it against DIR/NAME,
+   remove TEMPNAME if nonnull, and then exit.  */
+static void
+close_file(FILE *stream, char const *dir, char const *name,
+	   char const *tempname)
+{
+  char const *e = (ferror(stream) ? _("I/O error")
+		   : fclose(stream) != 0 ? strerror(errno) : NULL);
+  if (e) {
+    fprintf(stderr, "%s: %s%s%s%s%s\n", progname,
+	    dir ? dir : "", dir ? "/" : "",
+	    name ? name : "", name ? ": " : "",
+	    e);
+    if (tempname)
+      remove(tempname);
+    exit(EXIT_FAILURE);
+  }
+}
+
+static ATTRIBUTE_NORETURN void
+usage(FILE *stream, int status)
+{
+  fprintf(stream,
+	  _("%s: usage is %s [ --version ] [ --help ] [ -v ] \\\n"
+	    "\t[ -b {slim|fat} ] [ -d directory ] [ -l localtime ]"
+	    " [ -L leapseconds ] \\\n"
+	    "\t[ -p posixrules ] [ -r '[@lo][/@hi]' ] [ -R '@hi' ] \\\n"
+	    "\t[ -t localtime-link ] [ -D ] [ -g gid ] [ -u uid ] \\\n"
+	    "\t[ filename ... ]\n\n"
+	    "Report bugs to %s.\n"),
+	  progname, progname, REPORT_BUGS_TO);
+  if (status == EXIT_SUCCESS)
+    close_file(stream, NULL, NULL, NULL);
+  exit(status);
+}
+
+/* Change the working directory to DIR, possibly creating DIR and its
+   ancestors.  After this is done, all files are accessed with names
+   relative to DIR.  */
+static void
+change_directory(char const *dir)
+{
+  if (chdir(dir) != 0) {
+    int chdir_errno = errno;
+    if (chdir_errno == ENOENT) {
+      mkdirs(dir, false);
+      chdir_errno = chdir(dir) == 0 ? 0 : errno;
+    }
+    if (chdir_errno != 0) {
+      fprintf(stderr, _("%s: Can't chdir to %s: %s\n"),
+	      progname, dir, strerror(chdir_errno));
+      exit(EXIT_FAILURE);
+    }
+  }
+}
+
+/* Compare the two links A and B, for a stable sort by link name.  */
+static int
+qsort_linkcmp(void const *a, void const *b)
+{
+  struct link const *l = a;
+  struct link const *m = b;
+  int cmp = strcmp(l->l_linkname, m->l_linkname);
+  if (cmp)
+    return cmp;
+
+  /* The link names are the same.  Make the sort stable by comparing
+     file numbers (where subtraction cannot overflow) and possibly
+     line numbers (where it can).  */
+  cmp = l->l_filenum - m->l_filenum;
+  if (cmp)
+    return cmp;
+  return (l->l_linenum > m->l_linenum) - (l->l_linenum < m->l_linenum);
+}
+
+/* Compare the string KEY to the link B, for bsearch.  */
+static int
+bsearch_linkcmp(void const *key, void const *b)
+{
+  struct link const *m = b;
+  return strcmp(key, m->l_linkname);
+}
+
+/* Make the links specified by the Link lines.  */
+static void
+make_links(void)
+{
+  ptrdiff_t i, j, nalinks, pass_size;
+  if (1 < nlinks)
+    qsort(links, nlinks, sizeof *links, qsort_linkcmp);
+
+  /* Ignore each link superseded by a later link with the same name.  */
+  j = 0;
+  for (i = 0; i < nlinks; i++) {
+    while (i + 1 < nlinks
+	   && strcmp(links[i].l_linkname, links[i + 1].l_linkname) == 0)
+      i++;
+    links[j++] = links[i];
+  }
+  nlinks = pass_size = j;
+
+  /* Walk through the link array making links.  However,
+     if a link's target has not been made yet, append a copy to the
+     end of the array.  The end of the array will gradually fill
+     up with a small sorted subsequence of not-yet-made links.
+     nalinks counts all the links in the array, including copies.
+     When we reach the copied subsequence, it may still contain
+     a link to a not-yet-made link, so the process repeats.
+     At any given point in time, the link array consists of the
+     following subregions, where 0 <= i <= j <= nalinks and
+     0 <= nlinks <= nalinks:
+
+       0 .. (i - 1):
+	 links that either have been made, or have been copied to a
+	 later point point in the array (this later point can be in
+	 any of the three subregions)
+       i .. (j - 1):
+	 not-yet-made links for this pass
+       j .. (nalinks - 1):
+	 not-yet-made links that this pass has skipped because
+	 they were links to not-yet-made links
+
+     The first subregion might not be sorted if nlinks < i;
+     the other two subregions are sorted.  This algorithm does
+     not alter entries 0 .. (nlinks - 1), which remain sorted.
+
+     If there are L links, this algorithm is O(C*L*log(L)) where
+     C is the length of the longest link chain.  Usually C is
+     short (e.g., 3) though its worst-case value is L.  */
+
+  j = nalinks = nlinks;
+
+  for (i = 0; i < nalinks; i++) {
+    struct link *l;
+
+    eat(links[i].l_filenum, links[i].l_linenum);
+
+    /* If this pass examined all its links, start the next pass.  */
+    if (i == j) {
+      if (nalinks - i == pass_size) {
+	error(_("\"Link %s %s\" is part of a link cycle"),
+	      links[i].l_target, links[i].l_linkname);
+	break;
+      }
+      j = nalinks;
+      pass_size = nalinks - i;
+    }
+
+    /* Diagnose self links, which the cycle detection algorithm would not
+       otherwise catch.  */
+    if (strcmp(links[i].l_target, links[i].l_linkname) == 0) {
+      error(_("link %s targets itself"), links[i].l_target);
+      continue;
+    }
+
+    /* Make this link unless its target has not been made yet.  */
+    l = bsearch(links[i].l_target, &links[i + 1], j - (i + 1),
+		sizeof *links, bsearch_linkcmp);
+    if (!l)
+      l = bsearch(links[i].l_target, &links[j], nalinks - j,
+		  sizeof *links, bsearch_linkcmp);
+    if (!l)
+      dolink(links[i].l_target, links[i].l_linkname, false);
+    else {
+      /* The link target has not been made yet; copy the link to the end.  */
+      links = growalloc(links, sizeof *links, nalinks, &nlinks_alloc);
+      links[nalinks++] = links[i];
+    }
+
+    if (noise && i < nlinks) {
+      if (l)
+	warning(_("link %s targeting link %s mishandled by pre-2023 zic"),
+		links[i].l_linkname, links[i].l_target);
+      else if (bsearch(links[i].l_target, links, nlinks, sizeof *links,
+		       bsearch_linkcmp))
+	warning(_("link %s targeting link %s"),
+		links[i].l_linkname, links[i].l_target);
+    }
+  }
+}
+
+/* Simple signal handling: just set a flag that is checked
+   periodically outside critical sections.  To set up the handler,
+   prefer sigaction if available to close a signal race.  */
+
+static sig_atomic_t got_signal;
+
+static void
+signal_handler(int sig)
+{
+#ifndef SA_SIGINFO
+  signal(sig, signal_handler);
+#endif
+  got_signal = sig;
+}
+
+/* Arrange for SIGINT etc. to be caught by the handler.  */
+static void
+catch_signals(void)
+{
+  static int const signals[] = {
+#ifdef SIGHUP
+    SIGHUP,
+#endif
+    SIGINT,
+#ifdef SIGPIPE
+    SIGPIPE,
+#endif
+    SIGTERM
+  };
+  size_t i;
+  for (i = 0; i < sizeof signals / sizeof signals[0]; i++) {
+#ifdef SA_SIGINFO
+    struct sigaction act0, act;
+    act.sa_handler = signal_handler;
+    sigemptyset(&act.sa_mask);
+    act.sa_flags = 0;
+    if (sigaction(signals[i], &act, &act0) == 0
+	&& ! (act0.sa_flags & SA_SIGINFO) && act0.sa_handler == SIG_IGN) {
+      sigaction(signals[i], &act0, NULL);
+      got_signal = 0;
+    }
+#else
+    if (signal(signals[i], signal_handler) == SIG_IGN) {
+      signal(signals[i], SIG_IGN);
+      got_signal = 0;
+    }
+#endif
+  }
+}
+
+/* If a signal has arrived, terminate zic with appropriate status.  */
+static void
+check_for_signal(void)
+{
+  int sig = got_signal;
+  if (sig) {
+    signal(sig, SIG_DFL);
+    raise(sig);
+    abort(); /* A bug in 'raise'.  */
+  }
+}
+
+enum { TIME_T_BITS_IN_FILE = 64 };
+
+/* The minimum and maximum values representable in a TZif file.  */
+static zic_t const min_time = MINVAL(zic_t, TIME_T_BITS_IN_FILE);
+static zic_t const max_time = MAXVAL(zic_t, TIME_T_BITS_IN_FILE);
+
+/* The minimum, and one less than the maximum, values specified by
+   the -r option.  These default to MIN_TIME and MAX_TIME.  */
+static zic_t lo_time = MINVAL(zic_t, TIME_T_BITS_IN_FILE);
+static zic_t hi_time = MAXVAL(zic_t, TIME_T_BITS_IN_FILE);
+
+/* The time specified by the -R option, defaulting to MIN_TIME.  */
+static zic_t redundant_time = MINVAL(zic_t, TIME_T_BITS_IN_FILE);
+
+/* The time specified by an Expires line, or negative if no such line.  */
+static zic_t leapexpires = -1;
+
+/* Set the time range of the output to TIMERANGE.
+   Return true if successful.  */
+static bool
+timerange_option(char *timerange)
+{
+  intmax_t lo = min_time, hi = max_time;
+  char *lo_end = timerange, *hi_end;
+  if (*timerange == '@') {
+    errno = 0;
+    lo = strtoimax(timerange + 1, &lo_end, 10);
+    if (lo_end == timerange + 1 || (lo == INTMAX_MAX && errno == ERANGE))
+      return false;
+  }
+  hi_end = lo_end;
+  if (lo_end[0] == '/' && lo_end[1] == '@') {
+    errno = 0;
+    hi = strtoimax(lo_end + 2, &hi_end, 10);
+    if (hi_end == lo_end + 2 || hi == INTMAX_MIN)
+      return false;
+    hi -= ! (hi == INTMAX_MAX && errno == ERANGE);
+  }
+  if (*hi_end || hi < lo || max_time < lo || hi < min_time)
+    return false;
+  lo_time = max(lo, min_time);
+  hi_time = min(hi, max_time);
+  return true;
+}
+
+/* Generate redundant time stamps up to OPT.  Return true if successful.  */
+static bool
+redundant_time_option(char *opt)
+{
+  if (*opt == '@') {
+    intmax_t redundant;
+    char *opt_end;
+    redundant = strtoimax(opt + 1, &opt_end, 10);
+    if (opt_end != opt + 1 && !*opt_end) {
+      redundant_time = max(redundant_time, redundant);
+      return true;
+    }
+  }
+  return false;
+}
+
+static const char *	psxrules;
+static const char *	lcltime;
+static const char *	directory;
+static const char *	leapsec;
+static int		Dflag;
+static uid_t		uflag = (uid_t)-1;
+static gid_t		gflag = (gid_t)-1;
+static mode_t		mflag = (S_IRUSR | S_IRGRP | S_IROTH
+				 | S_IWUSR);
+static const char *	tzdefault;
+
+/* -1 if the TZif output file should be slim, 0 if default, 1 if the
+   output should be fat for backward compatibility.  ZIC_BLOAT_DEFAULT
+   determines the default.  */
+static int bloat;
+
+static bool
+want_bloat(void)
+{
+  return 0 <= bloat;
+}
+
+#ifndef ZIC_BLOAT_DEFAULT
+# define ZIC_BLOAT_DEFAULT "slim"
+#endif
+
+int
+main(int argc, char **argv)
+{
+	register int c, k;
+	register ptrdiff_t i, j;
+	bool timerange_given = false;
+
+#ifdef S_IWGRP
+	umask(umask(S_IWGRP | S_IWOTH) | (S_IWGRP | S_IWOTH));
+#endif
+#if HAVE_GETTEXT
+	setlocale(LC_ALL, "");
+# ifdef TZ_DOMAINDIR
+	bindtextdomain(TZ_DOMAIN, TZ_DOMAINDIR);
+# endif /* defined TEXTDOMAINDIR */
+	textdomain(TZ_DOMAIN);
+#endif /* HAVE_GETTEXT */
+	main_argv = argv;
+	progname = /* argv[0] ? argv[0] : */ "zic";
+	if (TYPE_BIT(zic_t) < 64) {
+		fprintf(stderr, "%s: %s\n", progname,
+			_("wild compilation-time specification of zic_t"));
+		return EXIT_FAILURE;
+	}
+	for (k = 1; k < argc; k++)
+		if (strcmp(argv[k], "--version") == 0) {
+			printf("zic %s%s\n", PKGVERSION, TZVERSION);
+			close_file(stdout, NULL, NULL, NULL);
+			return EXIT_SUCCESS;
+		} else if (strcmp(argv[k], "--help") == 0) {
+			usage(stdout, EXIT_SUCCESS);
+		}
+	while ((c = getopt(argc, argv, "Db:d:g:l:L:m:p:r:R:st:u:vy:")) != EOF
+	       && c != -1)
+		switch (c) {
+			default:
+				usage(stderr, EXIT_FAILURE);
+			case 'D':
+				Dflag = 1;
+				break;
+			case 'b':
+				if (strcmp(optarg, "slim") == 0) {
+				  if (0 < bloat)
+				    error(_("incompatible -b options"));
+				  bloat = -1;
+				} else if (strcmp(optarg, "fat") == 0) {
+				  if (bloat < 0)
+				    error(_("incompatible -b options"));
+				  bloat = 1;
+				} else
+				  error(_("invalid option: -b '%s'"), optarg);
+				break;
+			case 'd':
+				if (directory == NULL)
+					directory = optarg;
+				else {
+					fprintf(stderr,
+_("%s: More than one -d option specified\n"),
+						progname);
+					return EXIT_FAILURE;
+				}
+				break;
+			case 'g':
+				setgroup(&gflag, optarg);
+				break;
+			case 'l':
+				if (lcltime == NULL)
+					lcltime = optarg;
+				else {
+					fprintf(stderr,
+_("%s: More than one -l option specified\n"),
+						progname);
+					return EXIT_FAILURE;
+				}
+				break;
+			case 'm':
+			{
+				void *set = setmode(optarg);
+				if (set == NULL) {
+					fprintf(stderr,
+_("invalid file mode"));
+					return EXIT_FAILURE;
+				}
+				mflag = getmode(set, mflag);
+				free(set);
+				break;
+			}
+			case 'p':
+				if (psxrules == NULL)
+					psxrules = optarg;
+				else {
+					fprintf(stderr,
+_("%s: More than one -p option specified\n"),
+						progname);
+					return EXIT_FAILURE;
+				}
+				break;
+			case 't':
+				if (tzdefault != NULL) {
+				  fprintf(stderr,
+					  _("%s: More than one -t option"
+					    " specified\n"),
+					  progname);
+				  return EXIT_FAILURE;
+				}
+				tzdefault = optarg;
+				break;
+			case 'u':
+				setuser(&uflag, optarg);
+				break;
+			case 'y':
+				warning(_("-y ignored"));
+				break;
+			case 'L':
+				if (leapsec == NULL)
+					leapsec = optarg;
+				else {
+					fprintf(stderr,
+_("%s: More than one -L option specified\n"),
+						progname);
+					return EXIT_FAILURE;
+				}
+				break;
+			case 'v':
+				noise = true;
+				break;
+			case 'r':
+				if (timerange_given) {
+				  fprintf(stderr,
+_("%s: More than one -r option specified\n"),
+					  progname);
+				  return EXIT_FAILURE;
+				}
+				if (! timerange_option(optarg)) {
+				  fprintf(stderr,
+_("%s: invalid time range: %s\n"),
+					  progname, optarg);
+				  return EXIT_FAILURE;
+				}
+				timerange_given = true;
+				break;
+			case 'R':
+				if (! redundant_time_option(optarg)) {
+				  fprintf(stderr, _("%s: invalid time: %s\n"),
+					  progname, optarg);
+				  return EXIT_FAILURE;
+				}
+				break;
+			case 's':
+				warning(_("-s ignored"));
+				break;
+		}
+	if (optind == argc - 1 && strcmp(argv[optind], "=") == 0)
+		usage(stderr, EXIT_FAILURE);	/* usage message by request */
+	if (hi_time + (hi_time < ZIC_MAX) < redundant_time) {
+	  fprintf(stderr, _("%s: -R time exceeds -r cutoff\n"), progname);
+	  return EXIT_FAILURE;
+	}
+	if (bloat == 0) {
+	  static char const bloat_default[] = ZIC_BLOAT_DEFAULT;
+	  if (strcmp(bloat_default, "slim") == 0)
+	    bloat = -1;
+	  else if (strcmp(bloat_default, "fat") == 0)
+	    bloat = 1;
+	  else
+	    abort(); /* Configuration error.  */
+	}
+	if (directory == NULL)
+		directory = TZDIR;
+	if (tzdefault == NULL)
+		tzdefault = TZDEFAULT;
+
+	if (optind < argc && leapsec != NULL) {
+		infile(LEAPSEC_FILENUM, leapsec);
+		adjleap();
+	}
+
+	for (k = optind; k < argc; k++)
+	  infile(k, argv[k]);
+	if (errors)
+		return EXIT_FAILURE;
+	associate();
+	change_directory(directory);
+	catch_signals();
+	for (i = 0; i < nzones; i = j) {
+		/*
+		** Find the next non-continuation zone entry.
+		*/
+		for (j = i + 1; j < nzones && zones[j].z_name == NULL; ++j)
+			continue;
+		outzone(&zones[i], j - i);
+	}
+	make_links();
+	if (lcltime != NULL) {
+		eat(COMMAND_LINE_FILENUM, 1);
+		dolink(lcltime, tzdefault, true);
+	}
+	if (psxrules != NULL) {
+		eat(COMMAND_LINE_FILENUM, 1);
+		dolink(psxrules, TZDEFRULES, true);
+	}
+	if (warnings && (ferror(stderr) || fclose(stderr) != 0))
+	  return EXIT_FAILURE;
+	return errors ? EXIT_FAILURE : EXIT_SUCCESS;
+}
+
+static bool
+componentcheck(char const *name, char const *component,
+	       char const *component_end)
+{
+	enum { component_len_max = 14 };
+	ptrdiff_t component_len = component_end - component;
+	if (component_len == 0) {
+	  if (!*name)
+	    error(_("empty file name"));
+	  else
+	    error(_(component == name
+		     ? "file name '%s' begins with '/'"
+		     : *component_end
+		     ? "file name '%s' contains '//'"
+		     : "file name '%s' ends with '/'"),
+		   name);
+	  return false;
+	}
+	if (0 < component_len && component_len <= 2
+	    && component[0] == '.' && component_end[-1] == '.') {
+	  int len = component_len;
+	  error(_("file name '%s' contains '%.*s' component"),
+		name, len, component);
+	  return false;
+	}
+	if (noise) {
+	  if (0 < component_len && component[0] == '-')
+	    warning(_("file name '%s' component contains leading '-'"),
+		    name);
+	  if (component_len_max < component_len)
+	    warning(_("file name '%s' contains overlength component"
+		      " '%.*s...'"),
+		    name, component_len_max, component);
+	}
+	return true;
+}
+
+static bool
+namecheck(const char *name)
+{
+	register char const *cp;
+
+	/* Benign characters in a portable file name.  */
+	static char const benign[] =
+	  "-/_"
+	  "abcdefghijklmnopqrstuvwxyz"
+	  "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
+
+	/* Non-control chars in the POSIX portable character set,
+	   excluding the benign characters.  */
+	static char const printable_and_not_benign[] =
+	  " !\"#$%&'()*+,.0123456789:;<=>?@[\\]^`{|}~";
+
+	register char const *component = name;
+	for (cp = name; *cp; cp++) {
+		unsigned char c = *cp;
+		if (noise && !strchr(benign, c)) {
+			warning((strchr(printable_and_not_benign, c)
+				 ? _("file name '%s' contains byte '%c'")
+				 : _("file name '%s' contains byte '\\%o'")),
+				name, c);
+		}
+		if (c == '/') {
+			if (!componentcheck(name, component, cp))
+			  return false;
+			component = cp + 1;
+		}
+	}
+	return componentcheck(name, component, cp);
+}
+
+/* Return a random uint_fast64_t.  */
+static uint_fast64_t
+get_rand_u64(void)
+{
+#if HAVE_GETRANDOM
+  static uint_fast64_t entropy_buffer[max(1, 256 / sizeof(uint_fast64_t))];
+  static int nwords;
+  if (!nwords) {
+    ssize_t s;
+    do
+      s = getrandom(entropy_buffer, sizeof entropy_buffer, 0);
+    while (s < 0 && errno == EINTR);
+
+    nwords = s < 0 ? -1 : s / sizeof *entropy_buffer;
+  }
+  if (0 < nwords)
+    return entropy_buffer[--nwords];
+#endif
+
+  /* getrandom didn't work, so fall back on portable code that is
+     not the best because the seed isn't cryptographically random and
+     'rand' might not be cryptographically secure.  */
+  {
+    static bool initialized;
+    if (!initialized) {
+      srand(time(NULL));
+      initialized = true;
+    }
+  }
+
+  /* Return a random number if rand() yields a random number and in
+     the typical case where RAND_MAX is one less than a power of two.
+     In other cases this code yields a sort-of-random number.  */
+  {
+    uint_fast64_t rand_max = RAND_MAX,
+      nrand = rand_max < UINT_FAST64_MAX ? rand_max + 1 : 0,
+      rmod = INT_MAX < UINT_FAST64_MAX ? 0 : UINT_FAST64_MAX / nrand + 1,
+      r = 0, rmax = 0;
+
+    do {
+      uint_fast64_t rmax1 = rmax;
+      if (rmod) {
+	/* Avoid signed integer overflow on theoretical platforms
+	   where uint_fast64_t promotes to int.  */
+	rmax1 %= rmod;
+	r %= rmod;
+      }
+      rmax1 = nrand * rmax1 + rand_max;
+      r = nrand * r + rand();
+      rmax = rmax < rmax1 ? rmax1 : UINT_FAST64_MAX;
+    } while (rmax < UINT_FAST64_MAX);
+
+    return r;
+  }
+}
+
+/* Generate a randomish name in the same directory as *NAME.  If
+   *NAMEALLOC, put the name into *NAMEALLOC which is assumed to be
+   that returned by a previous call and is thus already almost set up
+   and equal to *NAME; otherwise, allocate a new name and put its
+   address into both *NAMEALLOC and *NAME.  */
+static void
+random_dirent(char const **name, char **namealloc)
+{
+  char const *src = *name;
+  char *dst = *namealloc;
+  static char const prefix[] = ".zic";
+  static char const alphabet[] =
+    "abcdefghijklmnopqrstuvwxyz"
+    "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
+    "0123456789";
+  enum { prefixlen = sizeof prefix - 1, alphabetlen = sizeof alphabet - 1 };
+  int suffixlen = 6;
+  char const *lastslash = strrchr(src, '/');
+  ptrdiff_t dirlen = lastslash ? lastslash + 1 - src : 0;
+  int i;
+  uint_fast64_t r;
+  uint_fast64_t base = alphabetlen;
+
+  /* BASE**6 */
+  uint_fast64_t base__6 = base * base * base * base * base * base;
+
+  /* The largest uintmax_t that is a multiple of BASE**6.  Any random
+     uintmax_t value that is this value or greater, yields a biased
+     remainder when divided by BASE**6.  UNFAIR_MIN equals the
+     mathematical value of ((UINTMAX_MAX + 1) - (UINTMAX_MAX + 1) % BASE**6)
+     computed without overflow.  */
+  uint_fast64_t unfair_min = - ((UINTMAX_MAX % base__6 + 1) % base__6);
+
+  if (!dst) {
+    dst = emalloc(size_sum(dirlen, prefixlen + suffixlen + 1));
+    memcpy(dst, src, dirlen);
+    memcpy(dst + dirlen, prefix, prefixlen);
+    dst[dirlen + prefixlen + suffixlen] = '\0';
+    *name = *namealloc = dst;
+  }
+
+  do
+    r = get_rand_u64();
+  while (unfair_min <= r);
+
+  for (i = 0; i < suffixlen; i++) {
+    dst[dirlen + prefixlen + i] = alphabet[r % alphabetlen];
+    r /= alphabetlen;
+  }
+}
+
+/* Prepare to write to the file *OUTNAME, using *TEMPNAME to store the
+   name of the temporary file that will eventually be renamed to
+   *OUTNAME.  Assign the temporary file's name to both *OUTNAME and
+   *TEMPNAME.  If *TEMPNAME is null, allocate the name of any such
+   temporary file; otherwise, reuse *TEMPNAME's storage, which is
+   already set up and only needs its trailing suffix updated.  */
+static FILE *
+open_outfile(char const **outname, char **tempname)
+{
+#if __STDC_VERSION__ < 201112
+  static char const fopen_mode[] = "wb";
+#else
+  static char const fopen_mode[] = "wbx";
+#endif
+
+  FILE *fp;
+  bool dirs_made = false;
+  if (!*tempname)
+    random_dirent(outname, tempname);
+
+  /*
+   * Remove old file, if any, to snap links.
+   */
+  if (remove(*outname) != 0 && errno != ENOENT && errno != EISDIR) {
+    fprintf(stderr, _("can't remove %s"), *outname);
+    exit(EXIT_FAILURE);
+  }
+
+  while (! (fp = fopen(*outname, fopen_mode))) {
+    int fopen_errno = errno;
+    if (fopen_errno == ENOENT && !dirs_made) {
+      mkdirs(*outname, true);
+      dirs_made = true;
+    } else if (fopen_errno == EEXIST)
+      random_dirent(outname, tempname);
+    else {
+      fprintf(stderr, _("%s: Can't create %s/%s: %s\n"),
+	      progname, directory, *outname, strerror(fopen_errno));
+      exit(EXIT_FAILURE);
+    }
+  }
+
+  return fp;
+}
+
+/* If TEMPNAME, the result is in the temporary file TEMPNAME even
+   though the user wanted it in NAME, so rename TEMPNAME to NAME.
+   Report an error and exit if there is trouble.  Also, free TEMPNAME.  */
+static void
+rename_dest(char *tempname, char const *name)
+{
+  if (tempname) {
+    if (rename(tempname, name) != 0) {
+      int rename_errno = errno;
+      remove(tempname);
+      fprintf(stderr, _("%s: rename to %s/%s: %s\n"),
+	      progname, directory, name, strerror(rename_errno));
+      exit(EXIT_FAILURE);
+    }
+    free(tempname);
+  }
+}
+
+/* Create symlink contents suitable for symlinking FROM to TO, as a
+   freshly allocated string.  FROM should be a relative file name, and
+   is relative to the global variable DIRECTORY.  TO can be either
+   relative or absolute.  */
+static char *
+relname(char const *target, char const *linkname)
+{
+  size_t i, taillen, dir_len = 0, dotdots = 0;
+  ptrdiff_t dotdotetcsize, linksize = min(PTRDIFF_MAX, SIZE_MAX);
+  char const *f = target;
+  char *result = NULL;
+  if (*linkname == '/') {
+    /* Make F absolute too.  */
+    size_t len = strlen(directory);
+    size_t lenslash = len + (len && directory[len - 1] != '/');
+    size_t targetsize = strlen(target) + 1;
+    linksize = size_sum(lenslash, targetsize);
+    f = result = emalloc(linksize);
+    memcpy(result, directory, len);
+    result[len] = '/';
+    memcpy(result + lenslash, target, targetsize);
+  }
+  for (i = 0; f[i] && f[i] == linkname[i]; i++)
+    if (f[i] == '/')
+      dir_len = i + 1;
+  for (; linkname[i]; i++)
+    dotdots += linkname[i] == '/' && linkname[i - 1] != '/';
+  taillen = strlen(f + dir_len);
+  dotdotetcsize = size_sum(size_product(dotdots, 3), taillen + 1);
+  if (dotdotetcsize <= linksize) {
+    if (!result)
+      result = emalloc(dotdotetcsize);
+    for (i = 0; i < dotdots; i++)
+      memcpy(result + 3 * i, "../", 3);
+    memmove(result + 3 * dotdots, f + dir_len, taillen + 1);
+  }
+  return result;
+}
+
+static void
+dolink(char const *target, char const *linkname, bool staysymlink)
+{
+	bool linkdirs_made = false;
+	int link_errno;
+	char *tempname = NULL;
+	char const *outname = linkname;
+
+	check_for_signal();
+
+	if (strcmp(target, "-") == 0) {
+	  if (remove(linkname) == 0 || errno == ENOENT || errno == ENOTDIR)
+	    return;
+	  else {
+	    char const *e = strerror(errno);
+	    fprintf(stderr, _("%s: Can't remove %s/%s: %s\n"),
+		    progname, directory, linkname, e);
+	    exit(EXIT_FAILURE);
+	  }
+	}
+
+	while (true) {
+	  if (linkat(AT_FDCWD, target, AT_FDCWD, outname, AT_SYMLINK_FOLLOW)
+	      == 0) {
+	    link_errno = 0;
+	    break;
+	  }
+	  link_errno = errno;
+	  if (link_errno == EXDEV || link_errno == ENOTSUP)
+	    break;
+
+	  if (link_errno == EEXIST) {
+	    staysymlink &= !tempname;
+	    random_dirent(&outname, &tempname);
+	    if (staysymlink && itssymlink(linkname))
+	      break;
+	  } else if (link_errno == ENOENT && !linkdirs_made) {
+	    mkdirs(linkname, true);
+	    linkdirs_made = true;
+	  } else {
+	    fprintf(stderr, _("%s: Can't link %s/%s to %s/%s: %s\n"),
+		    progname, directory, target, directory, outname,
+		    strerror(link_errno));
+	    exit(EXIT_FAILURE);
+	  }
+	}
+	if (link_errno != 0) {
+	  bool absolute = *target == '/';
+	  char *linkalloc = absolute ? NULL : relname(target, linkname);
+	  char const *contents = absolute ? target : linkalloc;
+	  int symlink_errno;
+
+	  while (true) {
+	    if (symlink(contents, outname) == 0) {
+	      symlink_errno = 0;
+	      break;
+	    }
+	    symlink_errno = errno;
+	    if (symlink_errno == EEXIST)
+	      random_dirent(&outname, &tempname);
+	    else if (symlink_errno == ENOENT && !linkdirs_made) {
+	      mkdirs(linkname, true);
+	      linkdirs_made = true;
+	    } else
+	      break;
+	  }
+	  free(linkalloc);
+	  if (symlink_errno == 0) {
+	    if (link_errno != ENOTSUP && link_errno != EEXIST)
+	      warning(_("symbolic link used because hard link failed: %s"),
+		      strerror(link_errno));
+	  } else {
+	    FILE *fp, *tp;
+	    int c;
+	    fp = fopen(target, "rb");
+	    if (!fp) {
+	      char const *e = strerror(errno);
+	      fprintf(stderr, _("%s: Can't read %s/%s: %s\n"),
+		      progname, directory, target, e);
+	      exit(EXIT_FAILURE);
+	    }
+	    tp = open_outfile(&outname, &tempname);
+	    while ((c = getc(fp)) != EOF)
+	      putc(c, tp);
+	    close_file(tp, directory, linkname, tempname);
+	    close_file(fp, directory, target, NULL);
+	    if (link_errno != ENOTSUP)
+	      warning(_("copy used because hard link failed: %s"),
+		      strerror(link_errno));
+	    else if (symlink_errno != ENOTSUP)
+	      warning(_("copy used because symbolic link failed: %s"),
+		      strerror(symlink_errno));
+	  }
+	}
+	rename_dest(tempname, linkname);
+}
+
+/* Return true if NAME is a symbolic link.  */
+static bool
+itssymlink(char const *name)
+{
+  char c;
+  return 0 <= readlink(name, &c, 1);
+}
+
+/*
+** Associate sets of rules with zones.
+*/
+
+/*
+** Sort by rule name.
+*/
+
+static int
+rcomp(const void *cp1, const void *cp2)
+{
+  struct rule const *r1 = cp1, *r2 = cp2;
+  return strcmp(r1->r_name, r2->r_name);
+}
+
+static void
+associate(void)
+{
+	register struct zone *	zp;
+	register struct rule *	rp;
+	register ptrdiff_t i, j, base, out;
+
+	if (1 < nrules) {
+		qsort(rules, nrules, sizeof *rules, rcomp);
+		for (i = 0; i < nrules - 1; ++i) {
+			if (strcmp(rules[i].r_name,
+				rules[i + 1].r_name) != 0)
+					continue;
+			if (rules[i].r_filenum == rules[i + 1].r_filenum)
+					continue;
+			eat(rules[i].r_filenum, rules[i].r_linenum);
+			warning(_("same rule name in multiple files"));
+			eat(rules[i + 1].r_filenum, rules[i + 1].r_linenum);
+			warning(_("same rule name in multiple files"));
+			for (j = i + 2; j < nrules; ++j) {
+				if (strcmp(rules[i].r_name,
+					rules[j].r_name) != 0)
+						break;
+				if (rules[i].r_filenum == rules[j].r_filenum)
+						continue;
+				if (rules[i + 1].r_filenum
+				    == rules[j].r_filenum)
+						continue;
+				break;
+			}
+			i = j - 1;
+		}
+	}
+	for (i = 0; i < nzones; ++i) {
+		zp = &zones[i];
+		zp->z_rules = NULL;
+		zp->z_nrules = 0;
+	}
+	for (base = 0; base < nrules; base = out) {
+		rp = &rules[base];
+		for (out = base + 1; out < nrules; ++out)
+			if (strcmp(rp->r_name, rules[out].r_name) != 0)
+				break;
+		for (i = 0; i < nzones; ++i) {
+			zp = &zones[i];
+			if (strcmp(zp->z_rule, rp->r_name) != 0)
+				continue;
+			zp->z_rules = rp;
+			zp->z_nrules = out - base;
+		}
+	}
+	for (i = 0; i < nzones; ++i) {
+		zp = &zones[i];
+		if (zp->z_nrules == 0) {
+			/*
+			** Maybe we have a local standard time offset.
+			*/
+			eat(zp->z_filenum, zp->z_linenum);
+			zp->z_save = getsave(zp->z_rule, &zp->z_isdst);
+			/*
+			** Note, though, that if there's no rule,
+			** a '%s' in the format is a bad thing.
+			*/
+			if (zp->z_format_specifier == 's')
+				error("%s", _("%s in ruleless zone"));
+		}
+	}
+	if (errors)
+		exit(EXIT_FAILURE);
+}
+
+/* Read a text line from FP into BUF, which is of size BUFSIZE.
+   Terminate it with a NUL byte instead of a newline.
+   Return true if successful, false if EOF.
+   On error, report the error and exit.  */
+static bool
+inputline(FILE *fp, char *buf, ptrdiff_t bufsize)
+{
+  ptrdiff_t linelen = 0, ch;
+  while ((ch = getc(fp)) != '\n') {
+    if (ch < 0) {
+      if (ferror(fp)) {
+	error(_("input error"));
+	exit(EXIT_FAILURE);
+      }
+      if (linelen == 0)
+	return false;
+      error(_("unterminated line"));
+      exit(EXIT_FAILURE);
+    }
+    if (!ch) {
+      error(_("NUL input byte"));
+      exit(EXIT_FAILURE);
+    }
+    buf[linelen++] = ch;
+    if (linelen == bufsize) {
+      error(_("line too long"));
+      exit(EXIT_FAILURE);
+    }
+  }
+  buf[linelen] = '\0';
+  return true;
+}
+
+static void
+infile(int fnum, char const *name)
+{
+	register FILE *			fp;
+	register const struct lookup *	lp;
+	register bool			wantcont;
+	register lineno			num;
+
+	if (strcmp(name, "-") == 0) {
+		fp = stdin;
+	} else if ((fp = fopen(name, "r")) == NULL) {
+		const char *e = strerror(errno);
+
+		fprintf(stderr, _("%s: Can't open %s: %s\n"),
+			progname, name, e);
+		exit(EXIT_FAILURE);
+	}
+	wantcont = false;
+	for (num = 1; ; ++num) {
+		enum { bufsize_bound
+		  = (min(INT_MAX, min(PTRDIFF_MAX, SIZE_MAX))
+		     / FORMAT_LEN_GROWTH_BOUND) };
+		char buf[min(_POSIX2_LINE_MAX, bufsize_bound)];
+		int nfields;
+		char *fields[MAX_FIELDS];
+		eat(fnum, num);
+		if (!inputline(fp, buf, sizeof buf))
+		  break;
+		nfields = getfields(buf, fields,
+				    sizeof fields / sizeof *fields);
+		if (nfields == 0) {
+			/* nothing to do */
+		} else if (wantcont) {
+			wantcont = inzcont(fields, nfields);
+		} else {
+			struct lookup const *line_codes
+			  = fnum < 0 ? leap_line_codes : zi_line_codes;
+			lp = byword(fields[0], line_codes);
+			if (lp == NULL)
+				error(_("input line of unknown type"));
+			else switch (lp->l_value) {
+				case LC_RULE:
+					inrule(fields, nfields);
+					wantcont = false;
+					break;
+				case LC_ZONE:
+					wantcont = inzone(fields, nfields);
+					break;
+				case LC_LINK:
+					inlink(fields, nfields);
+					wantcont = false;
+					break;
+				case LC_LEAP:
+					inleap(fields, nfields);
+					wantcont = false;
+					break;
+				case LC_EXPIRES:
+					inexpires(fields, nfields);
+					wantcont = false;
+					break;
+				default: unreachable();
+			}
+		}
+	}
+	close_file(fp, NULL, filename(fnum), NULL);
+	if (wantcont)
+		error(_("expected continuation line not found"));
+}
+
+/*
+** Convert a string of one of the forms
+**	h	-h	hh:mm	-hh:mm	hh:mm:ss	-hh:mm:ss
+** into a number of seconds.
+** A null string maps to zero.
+** Call error with errstring and return zero on errors.
+*/
+
+static zic_t
+gethms(char const *string, char const *errstring)
+{
+	zic_t	hh;
+	int sign, mm = 0, ss = 0;
+	char hhx, mmx, ssx, xr = '0', xs;
+	int tenths = 0;
+	bool ok = true;
+
+	if (string == NULL || *string == '\0')
+		return 0;
+	if (*string == '-') {
+		sign = -1;
+		++string;
+	} else	sign = 1;
+	switch (sscanf(string,
+		       "%"SCNdZIC"%c%d%c%d%c%1d%*[0]%c%*[0123456789]%c",
+		       &hh, &hhx, &mm, &mmx, &ss, &ssx, &tenths, &xr, &xs)) {
+	  default: ok = false; break;
+	  case 8:
+	    ok = '0' <= xr && xr <= '9';
+	    ATTRIBUTE_FALLTHROUGH;
+	  case 7:
+	    ok &= ssx == '.';
+	    if (ok && noise)
+	      warning(_("fractional seconds rejected by"
+			" pre-2018 versions of zic"));
+	    ATTRIBUTE_FALLTHROUGH;
+	  case 5: ok &= mmx == ':'; ATTRIBUTE_FALLTHROUGH;
+	  case 3: ok &= hhx == ':'; ATTRIBUTE_FALLTHROUGH;
+	  case 1: break;
+	}
+	if (!ok) {
+			error("%s", errstring);
+			return 0;
+	}
+	if (hh < 0 ||
+		mm < 0 || mm >= MINSPERHOUR ||
+		ss < 0 || ss > SECSPERMIN) {
+			error("%s", errstring);
+			return 0;
+	}
+	if (ZIC_MAX / SECSPERHOUR < hh) {
+		error(_("time overflow"));
+		return 0;
+	}
+	ss += 5 + ((ss ^ 1) & (xr == '0')) <= tenths; /* Round to even.  */
+	if (noise && (hh > HOURSPERDAY ||
+		(hh == HOURSPERDAY && (mm != 0 || ss != 0))))
+warning(_("values over 24 hours not handled by pre-2007 versions of zic"));
+	return oadd(sign * hh * SECSPERHOUR,
+		    sign * (mm * SECSPERMIN + ss));
+}
+
+static zic_t
+getsave(char *field, bool *isdst)
+{
+  int dst = -1;
+  zic_t save;
+  ptrdiff_t fieldlen = strlen(field);
+  if (fieldlen != 0) {
+    char *ep = field + fieldlen - 1;
+    switch (*ep) {
+      case 'd': dst = 1; *ep = '\0'; break;
+      case 's': dst = 0; *ep = '\0'; break;
+    }
+  }
+  save = gethms(field, _("invalid saved time"));
+  *isdst = dst < 0 ? save != 0 : dst;
+  return save;
+}
+
+static void
+inrule(char **fields, int nfields)
+{
+	struct rule r;
+
+	if (nfields != RULE_FIELDS) {
+		error(_("wrong number of fields on Rule line"));
+		return;
+	}
+	switch (*fields[RF_NAME]) {
+	  case '\0':
+	  case ' ': case '\f': case '\n': case '\r': case '\t': case '\v':
+	  case '+': case '-':
+	  case '0': case '1': case '2': case '3': case '4':
+	  case '5': case '6': case '7': case '8': case '9':
+		error(_("Invalid rule name \"%s\""), fields[RF_NAME]);
+		return;
+	}
+	r.r_filenum = filenum;
+	r.r_linenum = linenum;
+	r.r_save = getsave(fields[RF_SAVE], &r.r_isdst);
+	if (!rulesub(&r, fields[RF_LOYEAR], fields[RF_HIYEAR],
+		     fields[RF_COMMAND], fields[RF_MONTH], fields[RF_DAY],
+		     fields[RF_TOD]))
+	  return;
+	r.r_name = estrdup(fields[RF_NAME]);
+	r.r_abbrvar = estrdup(fields[RF_ABBRVAR]);
+	if (max_abbrvar_len < strlen(r.r_abbrvar))
+		max_abbrvar_len = strlen(r.r_abbrvar);
+	rules = growalloc(rules, sizeof *rules, nrules, &nrules_alloc);
+	rules[nrules++] = r;
+}
+
+static bool
+inzone(char **fields, int nfields)
+{
+	register ptrdiff_t i;
+
+	if (nfields < ZONE_MINFIELDS || nfields > ZONE_MAXFIELDS) {
+		error(_("wrong number of fields on Zone line"));
+		return false;
+	}
+	if (lcltime != NULL && strcmp(fields[ZF_NAME], tzdefault) == 0) {
+		error(
+_("\"Zone %s\" line and -l option are mutually exclusive"),
+			tzdefault);
+		return false;
+	}
+	if (strcmp(fields[ZF_NAME], TZDEFRULES) == 0 && psxrules != NULL) {
+		error(
+_("\"Zone %s\" line and -p option are mutually exclusive"),
+			TZDEFRULES);
+		return false;
+	}
+	for (i = 0; i < nzones; ++i)
+		if (zones[i].z_name != NULL &&
+			strcmp(zones[i].z_name, fields[ZF_NAME]) == 0) {
+				error(_("duplicate zone name %s"
+					" (file \"%s\", line %"PRIdMAX")"),
+				      fields[ZF_NAME],
+				      filename(zones[i].z_filenum),
+				      zones[i].z_linenum);
+				return false;
+		}
+	return inzsub(fields, nfields, false);
+}
+
+static bool
+inzcont(char **fields, int nfields)
+{
+	if (nfields < ZONEC_MINFIELDS || nfields > ZONEC_MAXFIELDS) {
+		error(_("wrong number of fields on Zone continuation line"));
+		return false;
+	}
+	return inzsub(fields, nfields, true);
+}
+
+static bool
+inzsub(char **fields, int nfields, bool iscont)
+{
+	register char *		cp;
+	char *			cp1;
+	struct zone z;
+	int format_len;
+	register int		i_stdoff, i_rule, i_format;
+	register int		i_untilyear, i_untilmonth;
+	register int		i_untilday, i_untiltime;
+	register bool		hasuntil;
+
+	if (iscont) {
+		i_stdoff = ZFC_STDOFF;
+		i_rule = ZFC_RULE;
+		i_format = ZFC_FORMAT;
+		i_untilyear = ZFC_TILYEAR;
+		i_untilmonth = ZFC_TILMONTH;
+		i_untilday = ZFC_TILDAY;
+		i_untiltime = ZFC_TILTIME;
+	} else if (!namecheck(fields[ZF_NAME]))
+		return false;
+	else {
+		i_stdoff = ZF_STDOFF;
+		i_rule = ZF_RULE;
+		i_format = ZF_FORMAT;
+		i_untilyear = ZF_TILYEAR;
+		i_untilmonth = ZF_TILMONTH;
+		i_untilday = ZF_TILDAY;
+		i_untiltime = ZF_TILTIME;
+	}
+	z.z_filenum = filenum;
+	z.z_linenum = linenum;
+	z.z_stdoff = gethms(fields[i_stdoff], _("invalid UT offset"));
+	if ((cp = strchr(fields[i_format], '%')) != 0) {
+		if ((*++cp != 's' && *cp != 'z') || strchr(cp, '%')
+		    || strchr(fields[i_format], '/')) {
+			error(_("invalid abbreviation format"));
+			return false;
+		}
+	}
+	z.z_format_specifier = cp ? *cp : '\0';
+	format_len = strlen(fields[i_format]);
+	if (max_format_len < format_len)
+	  max_format_len = format_len;
+	hasuntil = nfields > i_untilyear;
+	if (hasuntil) {
+		z.z_untilrule.r_filenum = filenum;
+		z.z_untilrule.r_linenum = linenum;
+		if (!rulesub(
+			&z.z_untilrule,
+			fields[i_untilyear],
+			"only",
+			"",
+			(nfields > i_untilmonth) ?
+			fields[i_untilmonth] : "Jan",
+			(nfields > i_untilday) ? fields[i_untilday] : "1",
+			(nfields > i_untiltime) ? fields[i_untiltime] : "0"))
+		  return false;
+		z.z_untiltime = rpytime(&z.z_untilrule,
+			z.z_untilrule.r_loyear);
+		if (iscont && nzones > 0 &&
+			z.z_untiltime > min_time &&
+			z.z_untiltime < max_time &&
+			zones[nzones - 1].z_untiltime > min_time &&
+			zones[nzones - 1].z_untiltime < max_time &&
+			zones[nzones - 1].z_untiltime >= z.z_untiltime) {
+				error(_(
+"Zone continuation line end time is not after end time of previous line"
+					));
+				return false;
+		}
+	}
+	z.z_name = iscont ? NULL : estrdup(fields[ZF_NAME]);
+	z.z_rule = estrdup(fields[i_rule]);
+	z.z_format = cp1 = estrdup(fields[i_format]);
+	if (z.z_format_specifier == 'z') {
+	  cp1[cp - fields[i_format]] = 's';
+	  if (noise)
+	    warning(_("format '%s' not handled by pre-2015 versions of zic"),
+		    fields[i_format]);
+	}
+	zones = growalloc(zones, sizeof *zones, nzones, &nzones_alloc);
+	zones[nzones++] = z;
+	/*
+	** If there was an UNTIL field on this line,
+	** there's more information about the zone on the next line.
+	*/
+	return hasuntil;
+}
+
+static zic_t
+getleapdatetime(char **fields, bool expire_line)
+{
+	register const char *		cp;
+	register const struct lookup *	lp;
+	register zic_t			i, j;
+	zic_t				year;
+	int				month, day;
+	zic_t				dayoff, tod;
+	zic_t				t;
+	char xs;
+
+	dayoff = 0;
+	cp = fields[LP_YEAR];
+	if (sscanf(cp, "%"SCNdZIC"%c", &year, &xs) != 1) {
+		/*
+		** Leapin' Lizards!
+		*/
+		error(_("invalid leaping year"));
+		return -1;
+	}
+	if (!expire_line) {
+	    if (!leapseen || leapmaxyear < year)
+		leapmaxyear = year;
+	    if (!leapseen || leapminyear > year)
+		leapminyear = year;
+	    leapseen = true;
+	}
+	j = EPOCH_YEAR;
+	while (j != year) {
+		if (year > j) {
+			i = len_years[isleap(j)];
+			++j;
+		} else {
+			--j;
+			i = -len_years[isleap(j)];
+		}
+		dayoff = oadd(dayoff, i);
+	}
+	if ((lp = byword(fields[LP_MONTH], mon_names)) == NULL) {
+		error(_("invalid month name"));
+		return -1;
+	}
+	month = lp->l_value;
+	j = TM_JANUARY;
+	while (j != month) {
+		i = len_months[isleap(year)][j];
+		dayoff = oadd(dayoff, i);
+		++j;
+	}
+	cp = fields[LP_DAY];
+	if (sscanf(cp, "%d%c", &day, &xs) != 1 ||
+		day <= 0 || day > len_months[isleap(year)][month]) {
+			error(_("invalid day of month"));
+			return -1;
+	}
+	dayoff = oadd(dayoff, day - 1);
+	if (dayoff < min_time / SECSPERDAY) {
+		error(_("time too small"));
+		return -1;
+	}
+	if (dayoff > max_time / SECSPERDAY) {
+		error(_("time too large"));
+		return -1;
+	}
+	t = dayoff * SECSPERDAY;
+	tod = gethms(fields[LP_TIME], _("invalid time of day"));
+	t = tadd(t, tod);
+	if (t < 0)
+	  error(_("leap second precedes Epoch"));
+	return t;
+}
+
+static void
+inleap(char **fields, int nfields)
+{
+  if (nfields != LEAP_FIELDS)
+    error(_("wrong number of fields on Leap line"));
+  else {
+    zic_t t = getleapdatetime(fields, false);
+    if (0 <= t) {
+      struct lookup const *lp = byword(fields[LP_ROLL], leap_types);
+      if (!lp)
+	error(_("invalid Rolling/Stationary field on Leap line"));
+      else {
+	int correction = 0;
+	if (!fields[LP_CORR][0]) /* infile() turns "-" into "".  */
+	  correction = -1;
+	else if (strcmp(fields[LP_CORR], "+") == 0)
+	  correction = 1;
+	else
+	  error(_("invalid CORRECTION field on Leap line"));
+	if (correction)
+	  leapadd(t, correction, lp->l_value);
+      }
+    }
+  }
+}
+
+static void
+inexpires(char **fields, int nfields)
+{
+  if (nfields != EXPIRES_FIELDS)
+    error(_("wrong number of fields on Expires line"));
+  else if (0 <= leapexpires)
+    error(_("multiple Expires lines"));
+  else
+    leapexpires = getleapdatetime(fields, true);
+}
+
+static void
+inlink(char **fields, int nfields)
+{
+	struct link	l;
+
+	if (nfields != LINK_FIELDS) {
+		error(_("wrong number of fields on Link line"));
+		return;
+	}
+	if (*fields[LF_TARGET] == '\0') {
+		error(_("blank TARGET field on Link line"));
+		return;
+	}
+	if (! namecheck(fields[LF_LINKNAME]))
+	  return;
+	l.l_filenum = filenum;
+	l.l_linenum = linenum;
+	l.l_target = estrdup(fields[LF_TARGET]);
+	l.l_linkname = estrdup(fields[LF_LINKNAME]);
+	links = growalloc(links, sizeof *links, nlinks, &nlinks_alloc);
+	links[nlinks++] = l;
+}
+
+static bool
+rulesub(struct rule *rp, const char *loyearp, const char *hiyearp,
+	const char *typep, const char *monthp, const char *dayp,
+	const char *timep)
+{
+	register const struct lookup *	lp;
+	register const char *		cp;
+	register char *			dp;
+	register char *			ep;
+	char xs;
+
+	if ((lp = byword(monthp, mon_names)) == NULL) {
+		error(_("invalid month name"));
+		return false;
+	}
+	rp->r_month = lp->l_value;
+	rp->r_todisstd = false;
+	rp->r_todisut = false;
+	dp = estrdup(timep);
+	if (*dp != '\0') {
+		ep = dp + strlen(dp) - 1;
+		switch (lowerit(*ep)) {
+			case 's':	/* Standard */
+				rp->r_todisstd = true;
+				rp->r_todisut = false;
+				*ep = '\0';
+				break;
+			case 'w':	/* Wall */
+				rp->r_todisstd = false;
+				rp->r_todisut = false;
+				*ep = '\0';
+				break;
+			case 'g':	/* Greenwich */
+			case 'u':	/* Universal */
+			case 'z':	/* Zulu */
+				rp->r_todisstd = true;
+				rp->r_todisut = true;
+				*ep = '\0';
+				break;
+		}
+	}
+	rp->r_tod = gethms(dp, _("invalid time of day"));
+	free(dp);
+	/*
+	** Year work.
+	*/
+	cp = loyearp;
+	lp = byword(cp, begin_years);
+	rp->r_lowasnum = lp == NULL;
+	if (!rp->r_lowasnum) switch (lp->l_value) {
+		case YR_MINIMUM:
+			rp->r_loyear = ZIC_MIN;
+			break;
+		case YR_MAXIMUM:
+			rp->r_loyear = ZIC_MAX;
+			break;
+		default: unreachable();
+	} else if (sscanf(cp, "%"SCNdZIC"%c", &rp->r_loyear, &xs) != 1) {
+		error(_("invalid starting year"));
+		return false;
+	}
+	cp = hiyearp;
+	lp = byword(cp, end_years);
+	rp->r_hiwasnum = lp == NULL;
+	if (!rp->r_hiwasnum) switch (lp->l_value) {
+		case YR_MINIMUM:
+			rp->r_hiyear = ZIC_MIN;
+			break;
+		case YR_MAXIMUM:
+			rp->r_hiyear = ZIC_MAX;
+			break;
+		case YR_ONLY:
+			rp->r_hiyear = rp->r_loyear;
+			break;
+		default: unreachable();
+	} else if (sscanf(cp, "%"SCNdZIC"%c", &rp->r_hiyear, &xs) != 1) {
+		error(_("invalid ending year"));
+		return false;
+	}
+	if (rp->r_loyear > rp->r_hiyear) {
+		error(_("starting year greater than ending year"));
+		return false;
+	}
+	if (*typep != '\0') {
+		error(_("year type \"%s\" is unsupported; use \"-\" instead"),
+			typep);
+		return false;
+	}
+	/*
+	** Day work.
+	** Accept things such as:
+	**	1
+	**	lastSunday
+	**	last-Sunday (undocumented; warn about this)
+	**	Sun<=20
+	**	Sun>=7
+	*/
+	dp = estrdup(dayp);
+	if ((lp = byword(dp, lasts)) != NULL) {
+		rp->r_dycode = DC_DOWLEQ;
+		rp->r_wday = lp->l_value;
+		rp->r_dayofmonth = len_months[1][rp->r_month];
+	} else {
+		if ((ep = strchr(dp, '<')) != 0)
+			rp->r_dycode = DC_DOWLEQ;
+		else if ((ep = strchr(dp, '>')) != 0)
+			rp->r_dycode = DC_DOWGEQ;
+		else {
+			ep = dp;
+			rp->r_dycode = DC_DOM;
+		}
+		if (rp->r_dycode != DC_DOM) {
+			*ep++ = 0;
+			if (*ep++ != '=') {
+				error(_("invalid day of month"));
+				free(dp);
+				return false;
+			}
+			if ((lp = byword(dp, wday_names)) == NULL) {
+				error(_("invalid weekday name"));
+				free(dp);
+				return false;
+			}
+			rp->r_wday = lp->l_value;
+		}
+		if (sscanf(ep, "%d%c", &rp->r_dayofmonth, &xs) != 1 ||
+			rp->r_dayofmonth <= 0 ||
+			(rp->r_dayofmonth > len_months[1][rp->r_month])) {
+				error(_("invalid day of month"));
+				free(dp);
+				return false;
+		}
+	}
+	free(dp);
+	return true;
+}
+
+static void
+convert(uint_fast32_t val, char *buf)
+{
+	register int	i;
+	register int	shift;
+	unsigned char *const b = (unsigned char *) buf;
+
+	for (i = 0, shift = 24; i < 4; ++i, shift -= 8)
+	  b[i] = (val >> shift) & 0xff;
+}
+
+static void
+convert64(uint_fast64_t val, char *buf)
+{
+	register int	i;
+	register int	shift;
+	unsigned char *const b = (unsigned char *) buf;
+
+	for (i = 0, shift = 56; i < 8; ++i, shift -= 8)
+	  b[i] = (val >> shift) & 0xff;
+}
+
+static void
+puttzcode(zic_t val, FILE *fp)
+{
+	char	buf[4];
+
+	convert(val, buf);
+	fwrite(buf, sizeof buf, 1, fp);
+}
+
+static void
+puttzcodepass(zic_t val, FILE *fp, int pass)
+{
+  if (pass == 1)
+    puttzcode(val, fp);
+  else {
+	char	buf[8];
+
+	convert64(val, buf);
+	fwrite(buf, sizeof buf, 1, fp);
+  }
+}
+
+static int
+atcomp(const void *avp, const void *bvp)
+{
+  struct attype const *ap = avp, *bp = bvp;
+  zic_t a = ap->at, b = bp->at;
+  return a < b ? -1 : a > b;
+}
+
+struct timerange {
+  int defaulttype;
+  ptrdiff_t base, count;
+  int leapbase, leapcount;
+  bool leapexpiry;
+};
+
+static struct timerange
+limitrange(struct timerange r, zic_t lo, zic_t hi,
+	   zic_t const *ats, unsigned char const *types)
+{
+  /* Omit ordinary transitions < LO.  */
+  while (0 < r.count && ats[r.base] < lo) {
+    r.defaulttype = types[r.base];
+    r.count--;
+    r.base++;
+  }
+
+  /* Omit as many initial leap seconds as possible, such that the
+     first leap second in the truncated list is <= LO, and is a
+     positive leap second if and only if it has a positive correction.
+     This supports common TZif readers that assume that the first leap
+     second is positive if and only if its correction is positive.  */
+  while (1 < r.leapcount && trans[r.leapbase + 1] <= lo) {
+    r.leapcount--;
+    r.leapbase++;
+  }
+  while (0 < r.leapbase
+	 && ((corr[r.leapbase - 1] < corr[r.leapbase])
+	     != (0 < corr[r.leapbase]))) {
+    r.leapcount++;
+    r.leapbase--;
+  }
+
+
+  /* Omit ordinary and leap second transitions greater than HI + 1.  */
+  if (hi < max_time) {
+    while (0 < r.count && hi + 1 < ats[r.base + r.count - 1])
+      r.count--;
+    while (0 < r.leapcount && hi + 1 < trans[r.leapbase + r.leapcount - 1])
+      r.leapcount--;
+  }
+
+  /* Determine whether to append an expiration to the leap second table.  */
+  r.leapexpiry = 0 <= leapexpires && leapexpires - 1 <= hi;
+
+  return r;
+}
+
+static void
+writezone(const char *const name, const char *const string, char version,
+	  int defaulttype)
+{
+	register FILE *			fp;
+	register ptrdiff_t		i, j;
+	register size_t			u;
+	register int			pass;
+	char *tempname = NULL;
+	char const *outname = name;
+
+	/* Allocate the ATS and TYPES arrays via a single malloc,
+	   as this is a bit faster.  Do not malloc(0) if !timecnt,
+	   as that might return NULL even on success.  */
+	zic_t *ats = emalloc(align_to(size_product(timecnt + !timecnt,
+						   sizeof *ats + 1),
+				      alignof(zic_t)));
+	void *typesptr = ats + timecnt;
+	unsigned char *types = typesptr;
+	struct timerange rangeall = {0}, range32, range64;
+
+	/*
+	** Sort.
+	*/
+	if (timecnt > 1)
+		qsort(attypes, timecnt, sizeof *attypes, atcomp);
+	/*
+	** Optimize.
+	*/
+	{
+		ptrdiff_t fromi, toi;
+
+		toi = 0;
+		fromi = 0;
+		for ( ; fromi < timecnt; ++fromi) {
+			if (toi != 0
+			    && ((attypes[fromi].at
+				 + utoffs[attypes[toi - 1].type])
+				<= (attypes[toi - 1].at
+				    + utoffs[toi == 1 ? 0
+					     : attypes[toi - 2].type]))) {
+					attypes[toi - 1].type =
+						attypes[fromi].type;
+					continue;
+			}
+			if (toi == 0
+			    || attypes[fromi].dontmerge
+			    || (utoffs[attypes[toi - 1].type]
+				!= utoffs[attypes[fromi].type])
+			    || (isdsts[attypes[toi - 1].type]
+				!= isdsts[attypes[fromi].type])
+			    || (desigidx[attypes[toi - 1].type]
+				!= desigidx[attypes[fromi].type]))
+					attypes[toi++] = attypes[fromi];
+		}
+		timecnt = toi;
+	}
+
+	if (noise && timecnt > 1200) {
+	  if (timecnt > TZ_MAX_TIMES)
+		warning(_("reference clients mishandle"
+			  " more than %d transition times"),
+			TZ_MAX_TIMES);
+	  else
+		warning(_("pre-2014 clients may mishandle"
+			  " more than 1200 transition times"));
+	}
+	/*
+	** Transfer.
+	*/
+	for (i = 0; i < timecnt; ++i) {
+		ats[i] = attypes[i].at;
+		types[i] = attypes[i].type;
+	}
+
+	/*
+	** Correct for leap seconds.
+	*/
+	for (i = 0; i < timecnt; ++i) {
+		j = leapcnt;
+		while (--j >= 0)
+			if (ats[i] > trans[j] - corr[j]) {
+				ats[i] = tadd(ats[i], corr[j]);
+				break;
+			}
+	}
+
+	rangeall.defaulttype = defaulttype;
+	rangeall.count = timecnt;
+	rangeall.leapcount = leapcnt;
+	range64 = limitrange(rangeall, lo_time,
+			     max(hi_time,
+				 redundant_time - (ZIC_MIN < redundant_time)),
+			     ats, types);
+	range32 = limitrange(range64, ZIC32_MIN, ZIC32_MAX, ats, types);
+
+	/* TZif version 4 is needed if a no-op transition is appended to
+	   indicate the expiration of the leap second table, or if the first
+	   leap second transition is not to a +1 or -1 correction.  */
+	for (pass = 1; pass <= 2; pass++) {
+	  struct timerange const *r = pass == 1 ? &range32 : &range64;
+	  if (pass == 1 && !want_bloat())
+	    continue;
+	  if (r->leapexpiry) {
+	    if (noise)
+	      warning(_("%s: pre-2021b clients may mishandle"
+			" leap second expiry"),
+		      name);
+	    version = '4';
+	  }
+	  if (0 < r->leapcount
+	      && corr[r->leapbase] != 1 && corr[r->leapbase] != -1) {
+	    if (noise)
+	      warning(_("%s: pre-2021b clients may mishandle"
+			" leap second table truncation"),
+		      name);
+	    version = '4';
+	  }
+	  if (version == '4')
+	    break;
+	}
+
+	fp = open_outfile(&outname, &tempname);
+
+	for (pass = 1; pass <= 2; ++pass) {
+		register ptrdiff_t thistimei, thistimecnt, thistimelim;
+		register int	thisleapi, thisleapcnt, thisleaplim;
+		struct tzhead tzh;
+		int pretranstype = -1, thisdefaulttype;
+		bool locut, hicut, thisleapexpiry;
+		zic_t lo, thismin, thismax;
+		int old0;
+		char		omittype[TZ_MAX_TYPES];
+		int		typemap[TZ_MAX_TYPES];
+		int		thistypecnt, stdcnt, utcnt;
+		char		thischars[TZ_MAX_CHARS];
+		int		thischarcnt;
+		bool		toomanytimes;
+		int		indmap[TZ_MAX_CHARS];
+
+		if (pass == 1) {
+			thisdefaulttype = range32.defaulttype;
+			thistimei = range32.base;
+			thistimecnt = range32.count;
+			toomanytimes = thistimecnt >> 31 >> 1 != 0;
+			thisleapi = range32.leapbase;
+			thisleapcnt = range32.leapcount;
+			thisleapexpiry = range32.leapexpiry;
+			thismin = ZIC32_MIN;
+			thismax = ZIC32_MAX;
+		} else {
+			thisdefaulttype = range64.defaulttype;
+			thistimei = range64.base;
+			thistimecnt = range64.count;
+			toomanytimes = thistimecnt >> 31 >> 31 >> 2 != 0;
+			thisleapi = range64.leapbase;
+			thisleapcnt = range64.leapcount;
+			thisleapexpiry = range64.leapexpiry;
+			thismin = min_time;
+			thismax = max_time;
+		}
+		if (toomanytimes)
+		  error(_("too many transition times"));
+
+		locut = thismin < lo_time && lo_time <= thismax;
+		hicut = thismin <= hi_time && hi_time < thismax;
+		thistimelim = thistimei + thistimecnt;
+		memset(omittype, true, typecnt);
+
+		/* Determine whether to output a transition before the first
+		   transition in range.  This is needed when the output is
+		   truncated at the start, and is also useful when catering to
+		   buggy 32-bit clients that do not use time type 0 for
+		   timestamps before the first transition.  */
+		if ((locut || (pass == 1 && thistimei))
+		    && ! (thistimecnt && ats[thistimei] == lo_time)) {
+		  pretranstype = thisdefaulttype;
+		  omittype[pretranstype] = false;
+		}
+
+		/* Arguably the default time type in the 32-bit data
+		   should be range32.defaulttype, which is suited for
+		   timestamps just before ZIC32_MIN.  However, zic
+		   traditionally used the time type of the indefinite
+		   past instead.  Internet RFC 8532 says readers should
+		   ignore 32-bit data, so this discrepancy matters only
+		   to obsolete readers where the traditional type might
+		   be more appropriate even if it's "wrong".  So, use
+		   the historical zic value, unless -r specifies a low
+		   cutoff that excludes some 32-bit timestamps.  */
+		if (pass == 1 && lo_time <= thismin)
+		  thisdefaulttype = range64.defaulttype;
+
+		if (locut)
+		  thisdefaulttype = unspecifiedtype;
+		omittype[thisdefaulttype] = false;
+		for (i = thistimei; i < thistimelim; i++)
+		  omittype[types[i]] = false;
+		if (hicut)
+		  omittype[unspecifiedtype] = false;
+
+		/* Reorder types to make THISDEFAULTTYPE type 0.
+		   Use TYPEMAP to swap OLD0 and THISDEFAULTTYPE so that
+		   THISDEFAULTTYPE appears as type 0 in the output instead
+		   of OLD0.  TYPEMAP also omits unused types.  */
+		old0 = strlen(omittype);
+
+#ifndef LEAVE_SOME_PRE_2011_SYSTEMS_IN_THE_LURCH
+		/*
+		** For some pre-2011 systems: if the last-to-be-written
+		** standard (or daylight) type has an offset different from the
+		** most recently used offset,
+		** append an (unused) copy of the most recently used type
+		** (to help get global "altzone" and "timezone" variables
+		** set correctly).
+		*/
+		if (want_bloat()) {
+			register int	mrudst, mrustd, hidst, histd, type;
+
+			hidst = histd = mrudst = mrustd = -1;
+			if (0 <= pretranstype) {
+			  if (isdsts[pretranstype])
+			    mrudst = pretranstype;
+			  else
+			    mrustd = pretranstype;
+			}
+			for (i = thistimei; i < thistimelim; i++)
+				if (isdsts[types[i]])
+					mrudst = types[i];
+				else	mrustd = types[i];
+			for (i = old0; i < typecnt; i++) {
+			  int h = (i == old0 ? thisdefaulttype
+				   : i == thisdefaulttype ? old0 : i);
+			  if (!omittype[h]) {
+			    if (isdsts[h])
+			      hidst = i;
+			    else
+			      histd = i;
+			  }
+			}
+			if (hidst >= 0 && mrudst >= 0 && hidst != mrudst &&
+				utoffs[hidst] != utoffs[mrudst]) {
+					isdsts[mrudst] = -1;
+					type = addtype(utoffs[mrudst],
+						&chars[desigidx[mrudst]],
+						true,
+						ttisstds[mrudst],
+						ttisuts[mrudst]);
+					isdsts[mrudst] = 1;
+					omittype[type] = false;
+			}
+			if (histd >= 0 && mrustd >= 0 && histd != mrustd &&
+				utoffs[histd] != utoffs[mrustd]) {
+					isdsts[mrustd] = -1;
+					type = addtype(utoffs[mrustd],
+						&chars[desigidx[mrustd]],
+						false,
+						ttisstds[mrustd],
+						ttisuts[mrustd]);
+					isdsts[mrustd] = 0;
+					omittype[type] = false;
+			}
+		}
+#endif /* !defined LEAVE_SOME_PRE_2011_SYSTEMS_IN_THE_LURCH */
+		thistypecnt = 0;
+		for (i = old0; i < typecnt; i++)
+		  if (!omittype[i])
+		    typemap[i == old0 ? thisdefaulttype
+			    : i == thisdefaulttype ? old0 : i]
+		      = thistypecnt++;
+
+		for (u = 0; u < sizeof indmap / sizeof indmap[0]; ++u)
+			indmap[u] = -1;
+		thischarcnt = stdcnt = utcnt = 0;
+		for (i = old0; i < typecnt; i++) {
+			register char *	thisabbr;
+
+			if (omittype[i])
+				continue;
+			if (ttisstds[i])
+			  stdcnt = thistypecnt;
+			if (ttisuts[i])
+			  utcnt = thistypecnt;
+			if (indmap[desigidx[i]] >= 0)
+				continue;
+			thisabbr = &chars[desigidx[i]];
+			for (j = 0; j < thischarcnt; ++j)
+				if (strcmp(&thischars[j], thisabbr) == 0)
+					break;
+			if (j == thischarcnt) {
+				strcpy(&thischars[thischarcnt], thisabbr);
+				thischarcnt += strlen(thisabbr) + 1;
+			}
+			indmap[desigidx[i]] = j;
+		}
+		if (pass == 1 && !want_bloat()) {
+		  hicut = thisleapexpiry = false;
+		  pretranstype = -1;
+		  thistimecnt = thisleapcnt = 0;
+		  thistypecnt = thischarcnt = 1;
+		}
+#define DO(field)	fwrite(tzh.field, sizeof tzh.field, 1, fp)
+		memset(&tzh, 0, sizeof tzh);
+		memcpy(tzh.tzh_magic, TZ_MAGIC, sizeof tzh.tzh_magic);
+		tzh.tzh_version[0] = version;
+		convert(utcnt, tzh.tzh_ttisutcnt);
+		convert(stdcnt, tzh.tzh_ttisstdcnt);
+		convert(thisleapcnt + thisleapexpiry, tzh.tzh_leapcnt);
+		convert((0 <= pretranstype) + thistimecnt + hicut,
+			tzh.tzh_timecnt);
+		convert(thistypecnt, tzh.tzh_typecnt);
+		convert(thischarcnt, tzh.tzh_charcnt);
+		DO(tzh_magic);
+		DO(tzh_version);
+		DO(tzh_reserved);
+		DO(tzh_ttisutcnt);
+		DO(tzh_ttisstdcnt);
+		DO(tzh_leapcnt);
+		DO(tzh_timecnt);
+		DO(tzh_typecnt);
+		DO(tzh_charcnt);
+#undef DO
+		if (pass == 1 && !want_bloat()) {
+		  /* Output a minimal data block with just one time type.  */
+		  puttzcode(0, fp);	/* utoff */
+		  putc(0, fp);		/* dst */
+		  putc(0, fp);		/* index of abbreviation */
+		  putc(0, fp);		/* empty-string abbreviation */
+		  continue;
+		}
+
+		/* Output a LO_TIME transition if needed; see limitrange.
+		   But do not go below the minimum representable value
+		   for this pass.  */
+		lo = pass == 1 && lo_time < ZIC32_MIN ? ZIC32_MIN : lo_time;
+
+		if (0 <= pretranstype)
+		  puttzcodepass(lo, fp, pass);
+		for (i = thistimei; i < thistimelim; ++i) {
+		  puttzcodepass(ats[i], fp, pass);
+		}
+		if (hicut)
+		  puttzcodepass(hi_time + 1, fp, pass);
+		if (0 <= pretranstype)
+		  putc(typemap[pretranstype], fp);
+		for (i = thistimei; i < thistimelim; i++)
+		  putc(typemap[types[i]], fp);
+		if (hicut)
+		  putc(typemap[unspecifiedtype], fp);
+
+		for (i = old0; i < typecnt; i++) {
+		  int h = (i == old0 ? thisdefaulttype
+			   : i == thisdefaulttype ? old0 : i);
+		  if (!omittype[h]) {
+		    puttzcode(utoffs[h], fp);
+		    putc(isdsts[h], fp);
+		    putc(indmap[desigidx[h]], fp);
+		  }
+		}
+		if (thischarcnt != 0)
+			fwrite(thischars, sizeof thischars[0],
+				      thischarcnt, fp);
+		thisleaplim = thisleapi + thisleapcnt;
+		for (i = thisleapi; i < thisleaplim; ++i) {
+			register zic_t	todo;
+
+			if (roll[i]) {
+				if (timecnt == 0 || trans[i] < ats[0]) {
+					j = 0;
+					while (isdsts[j])
+						if (++j >= typecnt) {
+							j = 0;
+							break;
+						}
+				} else {
+					j = 1;
+					while (j < timecnt &&
+						trans[i] >= ats[j])
+							++j;
+					j = types[j - 1];
+				}
+				todo = tadd(trans[i], -utoffs[j]);
+			} else	todo = trans[i];
+			puttzcodepass(todo, fp, pass);
+			puttzcode(corr[i], fp);
+		}
+		if (thisleapexpiry) {
+		  /* Append a no-op leap correction indicating when the leap
+		     second table expires.  Although this does not conform to
+		     Internet RFC 8536, most clients seem to accept this and
+		     the plan is to amend the RFC to allow this in version 4
+		     TZif files.  */
+		  puttzcodepass(leapexpires, fp, pass);
+		  puttzcode(thisleaplim ? corr[thisleaplim - 1] : 0, fp);
+		}
+		if (stdcnt != 0)
+		  for (i = old0; i < typecnt; i++)
+			if (!omittype[i])
+				putc(ttisstds[i], fp);
+		if (utcnt != 0)
+		  for (i = old0; i < typecnt; i++)
+			if (!omittype[i])
+				putc(ttisuts[i], fp);
+	}
+	fprintf(fp, "\n%s\n", string);
+	close_file(fp, directory, name, tempname);
+	if (chmod(tempname, mflag) < 0) {
+		fprintf(stderr, _("cannot change mode of %s to %03o"),
+		    tempname, (unsigned)mflag);
+		exit(EXIT_FAILURE);
+	}
+	if ((uflag != (uid_t)-1 || gflag != (gid_t)-1)
+	    && chown(tempname, uflag, gflag) < 0) {
+		fprintf(stderr, _("cannot change ownership of %s"), 
+		    tempname);
+		exit(EXIT_FAILURE);
+	}
+	rename_dest(tempname, name);
+	free(ats);
+}
+
+static char const *
+abbroffset(char *buf, zic_t offset)
+{
+  char sign = '+';
+  int seconds, minutes;
+
+  if (offset < 0) {
+    offset = -offset;
+    sign = '-';
+  }
+
+  seconds = offset % SECSPERMIN;
+  offset /= SECSPERMIN;
+  minutes = offset % MINSPERHOUR;
+  offset /= MINSPERHOUR;
+  if (100 <= offset) {
+    error(_("%%z UT offset magnitude exceeds 99:59:59"));
+    return "%z";
+  } else {
+    char *p = buf;
+    *p++ = sign;
+    *p++ = '0' + offset / 10;
+    *p++ = '0' + offset % 10;
+    if (minutes | seconds) {
+      *p++ = '0' + minutes / 10;
+      *p++ = '0' + minutes % 10;
+      if (seconds) {
+	*p++ = '0' + seconds / 10;
+	*p++ = '0' + seconds % 10;
+      }
+    }
+    *p = '\0';
+    return buf;
+  }
+}
+
+static char const disable_percent_s[] = "";
+
+static ptrdiff_t
+doabbr(char *abbr, struct zone const *zp, char const *letters,
+       bool isdst, zic_t save, bool doquotes)
+{
+	register char *	cp;
+	register char *	slashp;
+	ptrdiff_t len;
+	char const *format = zp->z_format;
+
+	slashp = strchr(format, '/');
+	if (slashp == NULL) {
+	  char letterbuf[PERCENT_Z_LEN_BOUND + 1];
+	  if (zp->z_format_specifier == 'z')
+	    letters = abbroffset(letterbuf, zp->z_stdoff + save);
+	  else if (!letters)
+	    letters = "%s";
+	  else if (letters == disable_percent_s)
+	    return 0;
+	  sprintf(abbr, format, letters);
+	} else if (isdst) {
+		strcpy(abbr, slashp + 1);
+	} else {
+		memcpy(abbr, format, slashp - format);
+		abbr[slashp - format] = '\0';
+	}
+	len = strlen(abbr);
+	if (!doquotes)
+		return len;
+	for (cp = abbr; is_alpha(*cp); cp++)
+		continue;
+	if (len > 0 && *cp == '\0')
+		return len;
+	abbr[len + 2] = '\0';
+	abbr[len + 1] = '>';
+	memmove(abbr + 1, abbr, len);
+	abbr[0] = '<';
+	return len + 2;
+}
+
+static void
+updateminmax(const zic_t x)
+{
+	if (min_year > x)
+		min_year = x;
+	if (max_year < x)
+		max_year = x;
+}
+
+static int
+stringoffset(char *result, zic_t offset)
+{
+	register int	hours;
+	register int	minutes;
+	register int	seconds;
+	bool negative = offset < 0;
+	int len = negative;
+
+	if (negative) {
+		offset = -offset;
+		result[0] = '-';
+	}
+	seconds = offset % SECSPERMIN;
+	offset /= SECSPERMIN;
+	minutes = offset % MINSPERHOUR;
+	offset /= MINSPERHOUR;
+	hours = offset;
+	if (hours >= HOURSPERDAY * DAYSPERWEEK) {
+		result[0] = '\0';
+		return 0;
+	}
+	len += sprintf(result + len, "%d", hours);
+	if (minutes != 0 || seconds != 0) {
+		len += sprintf(result + len, ":%02d", minutes);
+		if (seconds != 0)
+			len += sprintf(result + len, ":%02d", seconds);
+	}
+	return len;
+}
+
+static int
+stringrule(char *result, struct rule *const rp, zic_t save, zic_t stdoff)
+{
+	register zic_t	tod = rp->r_tod;
+	register int	compat = 0;
+
+	if (rp->r_dycode == DC_DOM) {
+		register int	month, total;
+
+		if (rp->r_dayofmonth == 29 && rp->r_month == TM_FEBRUARY)
+			return -1;
+		total = 0;
+		for (month = 0; month < rp->r_month; ++month)
+			total += len_months[0][month];
+		/* Omit the "J" in Jan and Feb, as that's shorter.  */
+		if (rp->r_month <= 1)
+		  result += sprintf(result, "%d", total + rp->r_dayofmonth - 1);
+		else
+		  result += sprintf(result, "J%d", total + rp->r_dayofmonth);
+	} else {
+		register int	week;
+		register int	wday = rp->r_wday;
+		register int	wdayoff;
+
+		if (rp->r_dycode == DC_DOWGEQ) {
+			wdayoff = (rp->r_dayofmonth - 1) % DAYSPERWEEK;
+			if (wdayoff)
+				compat = 2013;
+			wday -= wdayoff;
+			tod += wdayoff * SECSPERDAY;
+			week = 1 + (rp->r_dayofmonth - 1) / DAYSPERWEEK;
+		} else if (rp->r_dycode == DC_DOWLEQ) {
+			if (rp->r_dayofmonth == len_months[1][rp->r_month])
+				week = 5;
+			else {
+				wdayoff = rp->r_dayofmonth % DAYSPERWEEK;
+				if (wdayoff)
+					compat = 2013;
+				wday -= wdayoff;
+				tod += wdayoff * SECSPERDAY;
+				week = rp->r_dayofmonth / DAYSPERWEEK;
+			}
+		} else	return -1;	/* "cannot happen" */
+		if (wday < 0)
+			wday += DAYSPERWEEK;
+		result += sprintf(result, "M%d.%d.%d",
+				  rp->r_month + 1, week, wday);
+	}
+	if (rp->r_todisut)
+	  tod += stdoff;
+	if (rp->r_todisstd && !rp->r_isdst)
+	  tod += save;
+	if (tod != 2 * SECSPERMIN * MINSPERHOUR) {
+		*result++ = '/';
+		if (! stringoffset(result, tod))
+			return -1;
+		if (tod < 0) {
+			if (compat < 2013)
+				compat = 2013;
+		} else if (SECSPERDAY <= tod) {
+			if (compat < 1994)
+				compat = 1994;
+		}
+	}
+	return compat;
+}
+
+static int
+rule_cmp(struct rule const *a, struct rule const *b)
+{
+	if (!a)
+		return -!!b;
+	if (!b)
+		return 1;
+	if (a->r_hiyear != b->r_hiyear)
+		return a->r_hiyear < b->r_hiyear ? -1 : 1;
+	if (a->r_hiyear == ZIC_MAX)
+		return 0;
+	if (a->r_month - b->r_month != 0)
+		return a->r_month - b->r_month;
+	return a->r_dayofmonth - b->r_dayofmonth;
+}
+
+static int
+stringzone(char *result, struct zone const *zpfirst, ptrdiff_t zonecount)
+{
+	register const struct zone *	zp;
+	register struct rule *		rp;
+	register struct rule *		stdrp;
+	register struct rule *		dstrp;
+	register ptrdiff_t		i;
+	register int			compat = 0;
+	register int			c;
+	int				offsetlen;
+	struct rule			stdr, dstr;
+	ptrdiff_t len;
+	int dstcmp;
+	struct rule *lastrp[2] = { NULL, NULL };
+	struct zone zstr[2];
+	struct zone const *stdzp;
+	struct zone const *dstzp;
+
+	result[0] = '\0';
+
+	/* Internet RFC 8536 section 5.1 says to use an empty TZ string if
+	   future timestamps are truncated.  */
+	if (hi_time < max_time)
+	  return -1;
+
+	zp = zpfirst + zonecount - 1;
+	for (i = 0; i < zp->z_nrules; ++i) {
+		struct rule **last;
+		int cmp;
+		rp = &zp->z_rules[i];
+		last = &lastrp[rp->r_isdst];
+		cmp = rule_cmp(*last, rp);
+		if (cmp < 0)
+		  *last = rp;
+		else if (cmp == 0)
+		  return -1;
+	}
+	stdrp = lastrp[false];
+	dstrp = lastrp[true];
+	dstcmp = zp->z_nrules ? rule_cmp(dstrp, stdrp) : zp->z_isdst ? 1 : -1;
+	stdzp = dstzp = zp;
+
+	if (dstcmp < 0) {
+	  /* Standard time all year.  */
+	  dstrp = NULL;
+	} else if (0 < dstcmp) {
+	  /* DST all year.  Use an abbreviation like
+	     "XXX3EDT4,0/0,J365/23" for EDT (-04) all year.  */
+	  zic_t save = dstrp ? dstrp->r_save : zp->z_save;
+	  if (0 <= save)
+	    {
+	      /* Positive DST, the typical case for all-year DST.
+		 Fake a timezone with negative DST.  */
+	      stdzp = &zstr[0];
+	      dstzp = &zstr[1];
+	      zstr[0].z_stdoff = zp->z_stdoff + 2 * save;
+	      zstr[0].z_format = "XXX";  /* Any 3 letters will do.  */
+	      zstr[0].z_format_specifier = 0;
+	      zstr[1].z_stdoff = zstr[0].z_stdoff;
+	      zstr[1].z_format = zp->z_format;
+	      zstr[1].z_format_specifier = zp->z_format_specifier;
+	    }
+	  dstr.r_month = TM_JANUARY;
+	  dstr.r_dycode = DC_DOM;
+	  dstr.r_dayofmonth = 1;
+	  dstr.r_tod = 0;
+	  dstr.r_todisstd = dstr.r_todisut = false;
+	  dstr.r_isdst = true;
+	  dstr.r_save = save < 0 ? save : -save;
+	  dstr.r_abbrvar = dstrp ? dstrp->r_abbrvar : NULL;
+	  stdr.r_month = TM_DECEMBER;
+	  stdr.r_dycode = DC_DOM;
+	  stdr.r_dayofmonth = 31;
+	  stdr.r_tod = SECSPERDAY + dstr.r_save;
+	  stdr.r_todisstd = stdr.r_todisut = false;
+	  stdr.r_isdst = false;
+	  stdr.r_save = 0;
+	  stdr.r_abbrvar = save < 0 && stdrp ? stdrp->r_abbrvar : NULL;
+	  dstrp = &dstr;
+	  stdrp = &stdr;
+	}
+	len = doabbr(result, stdzp, stdrp ? stdrp->r_abbrvar : NULL,
+		     false, 0, true);
+	offsetlen = stringoffset(result + len, - stdzp->z_stdoff);
+	if (! offsetlen) {
+		result[0] = '\0';
+		return -1;
+	}
+	len += offsetlen;
+	if (dstrp == NULL)
+		return compat;
+	len += doabbr(result + len, dstzp, dstrp->r_abbrvar,
+		      dstrp->r_isdst, dstrp->r_save, true);
+	if (dstrp->r_save != SECSPERMIN * MINSPERHOUR) {
+	  offsetlen = stringoffset(result + len,
+				   - (dstzp->z_stdoff + dstrp->r_save));
+	  if (! offsetlen) {
+	    result[0] = '\0';
+	    return -1;
+	  }
+	  len += offsetlen;
+	}
+	result[len++] = ',';
+	c = stringrule(result + len, dstrp, dstrp->r_save, stdzp->z_stdoff);
+	if (c < 0) {
+		result[0] = '\0';
+		return -1;
+	}
+	if (compat < c)
+		compat = c;
+	len += strlen(result + len);
+	result[len++] = ',';
+	c = stringrule(result + len, stdrp, dstrp->r_save, stdzp->z_stdoff);
+	if (c < 0) {
+		result[0] = '\0';
+		return -1;
+	}
+	if (compat < c)
+		compat = c;
+	return compat;
+}
+
+static void
+outzone(const struct zone *zpfirst, ptrdiff_t zonecount)
+{
+	register ptrdiff_t		i, j;
+	register zic_t			starttime, untiltime;
+	register bool			startttisstd;
+	register bool			startttisut;
+	register char *			startbuf;
+	register char *			ab;
+	register char *			envvar;
+	register int			max_abbr_len;
+	register int			max_envvar_len;
+	register bool			prodstic; /* all rules are min to max */
+	register int			compat;
+	register bool			do_extend;
+	register char			version;
+	ptrdiff_t lastatmax = -1;
+	zic_t max_year0;
+	int defaulttype = -1;
+
+	check_for_signal();
+
+	/* This cannot overflow; see FORMAT_LEN_GROWTH_BOUND.  */
+	max_abbr_len = 2 + max_format_len + max_abbrvar_len;
+	max_envvar_len = 2 * max_abbr_len + 5 * 9;
+
+	startbuf = emalloc(max_abbr_len + 1);
+	ab = emalloc(max_abbr_len + 1);
+	envvar = emalloc(max_envvar_len + 1);
+	INITIALIZE(untiltime);
+	INITIALIZE(starttime);
+	/*
+	** Now. . .finally. . .generate some useful data!
+	*/
+	timecnt = 0;
+	typecnt = 0;
+	charcnt = 0;
+	prodstic = zonecount == 1;
+	/*
+	** Thanks to Earl Chew
+	** for noting the need to unconditionally initialize startttisstd.
+	*/
+	startttisstd = false;
+	startttisut = false;
+	min_year = max_year = EPOCH_YEAR;
+	if (leapseen) {
+		updateminmax(leapminyear);
+		updateminmax(leapmaxyear + (leapmaxyear < ZIC_MAX));
+	}
+	for (i = 0; i < zonecount; ++i) {
+		struct zone const *zp = &zpfirst[i];
+		if (i < zonecount - 1)
+			updateminmax(zp->z_untilrule.r_loyear);
+		for (j = 0; j < zp->z_nrules; ++j) {
+			struct rule *rp = &zp->z_rules[j];
+			if (rp->r_lowasnum)
+				updateminmax(rp->r_loyear);
+			if (rp->r_hiwasnum)
+				updateminmax(rp->r_hiyear);
+			if (rp->r_lowasnum || rp->r_hiwasnum)
+				prodstic = false;
+		}
+	}
+	/*
+	** Generate lots of data if a rule can't cover all future times.
+	*/
+	compat = stringzone(envvar, zpfirst, zonecount);
+	version = compat < 2013 ? '2' : '3';
+	do_extend = compat < 0;
+	if (noise) {
+		if (!*envvar)
+			warning("%s %s",
+				_("no POSIX environment variable for zone"),
+				zpfirst->z_name);
+		else if (compat != 0) {
+			/* Circa-COMPAT clients, and earlier clients, might
+			   not work for this zone when given dates before
+			   1970 or after 2038.  */
+			warning(_("%s: pre-%d clients may mishandle"
+				  " distant timestamps"),
+				zpfirst->z_name, compat);
+		}
+	}
+	if (do_extend) {
+		/*
+		** Search through a couple of extra years past the obvious
+		** 400, to avoid edge cases.  For example, suppose a non-POSIX
+		** rule applies from 2012 onwards and has transitions in March
+		** and September, plus some one-off transitions in November
+		** 2013.  If zic looked only at the last 400 years, it would
+		** set max_year=2413, with the intent that the 400 years 2014
+		** through 2413 will be repeated.  The last transition listed
+		** in the tzfile would be in 2413-09, less than 400 years
+		** after the last one-off transition in 2013-11.  Two years
+		** might be overkill, but with the kind of edge cases
+		** available we're not sure that one year would suffice.
+		*/
+		enum { years_of_observations = YEARSPERREPEAT + 2 };
+
+		if (min_year >= ZIC_MIN + years_of_observations)
+			min_year -= years_of_observations;
+		else	min_year = ZIC_MIN;
+		if (max_year <= ZIC_MAX - years_of_observations)
+			max_year += years_of_observations;
+		else	max_year = ZIC_MAX;
+		/*
+		** Regardless of any of the above,
+		** for a "proDSTic" zone which specifies that its rules
+		** always have and always will be in effect,
+		** we only need one cycle to define the zone.
+		*/
+		if (prodstic) {
+			min_year = 1900;
+			max_year = min_year + years_of_observations;
+		}
+	}
+	max_year = max(max_year, (redundant_time / (SECSPERDAY * DAYSPERNYEAR)
+				  + EPOCH_YEAR + 1));
+	max_year0 = max_year;
+	if (want_bloat()) {
+	  /* For the benefit of older systems,
+	     generate data from 1900 through 2038.  */
+	  if (min_year > 1900)
+		min_year = 1900;
+	  if (max_year < 2038)
+		max_year = 2038;
+	}
+
+	if (min_time < lo_time || hi_time < max_time)
+	  unspecifiedtype = addtype(0, "-00", false, false, false);
+
+	for (i = 0; i < zonecount; ++i) {
+		struct rule *prevrp = NULL;
+		/*
+		** A guess that may well be corrected later.
+		*/
+		zic_t save = 0;
+		struct zone const *zp = &zpfirst[i];
+		bool usestart = i > 0 && (zp - 1)->z_untiltime > min_time;
+		bool useuntil = i < (zonecount - 1);
+		zic_t stdoff = zp->z_stdoff;
+		zic_t startoff = stdoff;
+		zic_t prevktime;
+		INITIALIZE(prevktime);
+		if (useuntil && zp->z_untiltime <= min_time)
+			continue;
+		eat(zp->z_filenum, zp->z_linenum);
+		*startbuf = '\0';
+		if (zp->z_nrules == 0) {
+			int type;
+			save = zp->z_save;
+			doabbr(startbuf, zp, NULL, zp->z_isdst, save, false);
+			type = addtype(oadd(zp->z_stdoff, save),
+				startbuf, zp->z_isdst, startttisstd,
+				startttisut);
+			if (usestart) {
+				addtt(starttime, type);
+				usestart = false;
+			} else
+				defaulttype = type;
+		} else {
+		  zic_t year;
+		  for (year = min_year; year <= max_year; ++year) {
+			if (useuntil && year > zp->z_untilrule.r_hiyear)
+				break;
+			/*
+			** Mark which rules to do in the current year.
+			** For those to do, calculate rpytime(rp, year);
+			** The former TYPE field was also considered here.
+			*/
+			for (j = 0; j < zp->z_nrules; ++j) {
+				zic_t one = 1;
+				zic_t y2038_boundary = one << 31;
+				struct rule *rp = &zp->z_rules[j];
+				eats(zp->z_filenum, zp->z_linenum,
+				     rp->r_filenum, rp->r_linenum);
+				rp->r_todo = year >= rp->r_loyear &&
+						year <= rp->r_hiyear;
+				if (rp->r_todo) {
+					rp->r_temp = rpytime(rp, year);
+					rp->r_todo
+					  = (rp->r_temp < y2038_boundary
+					     || year <= max_year0);
+				}
+			}
+			for ( ; ; ) {
+				register ptrdiff_t k;
+				register zic_t	jtime, ktime;
+				register zic_t	offset;
+				struct rule *rp;
+				int type;
+
+				INITIALIZE(ktime);
+				if (useuntil) {
+					/*
+					** Turn untiltime into UT
+					** assuming the current stdoff and
+					** save values.
+					*/
+					untiltime = zp->z_untiltime;
+					if (!zp->z_untilrule.r_todisut)
+						untiltime = tadd(untiltime,
+								 -stdoff);
+					if (!zp->z_untilrule.r_todisstd)
+						untiltime = tadd(untiltime,
+								 -save);
+				}
+				/*
+				** Find the rule (of those to do, if any)
+				** that takes effect earliest in the year.
+				*/
+				k = -1;
+				for (j = 0; j < zp->z_nrules; ++j) {
+					struct rule *r = &zp->z_rules[j];
+					if (!r->r_todo)
+						continue;
+					eats(zp->z_filenum, zp->z_linenum,
+					     r->r_filenum, r->r_linenum);
+					offset = r->r_todisut ? 0 : stdoff;
+					if (!r->r_todisstd)
+						offset = oadd(offset, save);
+					jtime = r->r_temp;
+					if (jtime == min_time ||
+						jtime == max_time)
+							continue;
+					jtime = tadd(jtime, -offset);
+					if (k < 0 || jtime < ktime) {
+						k = j;
+						ktime = jtime;
+					} else if (jtime == ktime) {
+					  char const *dup_rules_msg =
+					    _("two rules for same instant");
+					  eats(zp->z_filenum, zp->z_linenum,
+					       r->r_filenum, r->r_linenum);
+					  warning("%s", dup_rules_msg);
+					  r = &zp->z_rules[k];
+					  eats(zp->z_filenum, zp->z_linenum,
+					       r->r_filenum, r->r_linenum);
+					  error("%s", dup_rules_msg);
+					}
+				}
+				if (k < 0)
+					break;	/* go on to next year */
+				rp = &zp->z_rules[k];
+				rp->r_todo = false;
+				if (useuntil && ktime >= untiltime) {
+					if (!*startbuf
+					    && (oadd(zp->z_stdoff, rp->r_save)
+						== startoff))
+					  doabbr(startbuf, zp, rp->r_abbrvar,
+						 rp->r_isdst, rp->r_save,
+						 false);
+					break;
+				}
+				save = rp->r_save;
+				if (usestart && ktime == starttime)
+					usestart = false;
+				if (usestart) {
+					if (ktime < starttime) {
+						startoff = oadd(zp->z_stdoff,
+								save);
+						doabbr(startbuf, zp,
+							rp->r_abbrvar,
+							rp->r_isdst,
+							rp->r_save,
+							false);
+						continue;
+					}
+					if (*startbuf == '\0'
+					    && startoff == oadd(zp->z_stdoff,
+								save)) {
+							doabbr(startbuf,
+								zp,
+								rp->r_abbrvar,
+								rp->r_isdst,
+								rp->r_save,
+								false);
+					}
+				}
+				eats(zp->z_filenum, zp->z_linenum,
+				     rp->r_filenum, rp->r_linenum);
+				doabbr(ab, zp, rp->r_abbrvar,
+				       rp->r_isdst, rp->r_save, false);
+				offset = oadd(zp->z_stdoff, rp->r_save);
+				if (!want_bloat() && !useuntil && !do_extend
+				    && prevrp && lo_time <= prevktime
+				    && redundant_time <= ktime
+				    && rp->r_hiyear == ZIC_MAX
+				    && prevrp->r_hiyear == ZIC_MAX)
+				  break;
+				type = addtype(offset, ab, rp->r_isdst,
+					rp->r_todisstd, rp->r_todisut);
+				if (defaulttype < 0 && !rp->r_isdst)
+				  defaulttype = type;
+				if (rp->r_hiyear == ZIC_MAX
+				    && ! (0 <= lastatmax
+					  && ktime < attypes[lastatmax].at))
+				  lastatmax = timecnt;
+				addtt(ktime, type);
+				prevrp = rp;
+				prevktime = ktime;
+			}
+		  }
+		}
+		if (usestart) {
+			bool isdst = startoff != zp->z_stdoff;
+			if (*startbuf == '\0' && zp->z_format)
+			  doabbr(startbuf, zp, disable_percent_s,
+				 isdst, save, false);
+			eat(zp->z_filenum, zp->z_linenum);
+			if (*startbuf == '\0')
+error(_("can't determine time zone abbreviation to use just after until time"));
+			else {
+			  int type = addtype(startoff, startbuf, isdst,
+					     startttisstd, startttisut);
+			  if (defaulttype < 0 && !isdst)
+			    defaulttype = type;
+			  addtt(starttime, type);
+			}
+		}
+		/*
+		** Now we may get to set starttime for the next zone line.
+		*/
+		if (useuntil) {
+			startttisstd = zp->z_untilrule.r_todisstd;
+			startttisut = zp->z_untilrule.r_todisut;
+			starttime = zp->z_untiltime;
+			if (!startttisstd)
+			  starttime = tadd(starttime, -save);
+			if (!startttisut)
+			  starttime = tadd(starttime, -stdoff);
+		}
+	}
+	if (defaulttype < 0)
+	  defaulttype = 0;
+	if (0 <= lastatmax)
+	  attypes[lastatmax].dontmerge = true;
+	if (do_extend) {
+		/*
+		** If we're extending the explicitly listed observations
+		** for 400 years because we can't fill the POSIX-TZ field,
+		** check whether we actually ended up explicitly listing
+		** observations through that period.  If there aren't any
+		** near the end of the 400-year period, add a redundant
+		** one at the end of the final year, to make it clear
+		** that we are claiming to have definite knowledge of
+		** the lack of transitions up to that point.
+		*/
+		struct rule xr;
+		struct attype *lastat;
+		xr.r_month = TM_JANUARY;
+		xr.r_dycode = DC_DOM;
+		xr.r_dayofmonth = 1;
+		xr.r_tod = 0;
+		for (lastat = attypes, i = 1; i < timecnt; i++)
+			if (attypes[i].at > lastat->at)
+				lastat = &attypes[i];
+		if (!lastat || lastat->at < rpytime(&xr, max_year - 1)) {
+			addtt(rpytime(&xr, max_year + 1),
+			      lastat ? lastat->type : defaulttype);
+			attypes[timecnt - 1].dontmerge = true;
+		}
+	}
+	writezone(zpfirst->z_name, envvar, version, defaulttype);
+	free(startbuf);
+	free(ab);
+	free(envvar);
+}
+
+static void
+addtt(zic_t starttime, int type)
+{
+	attypes = growalloc(attypes, sizeof *attypes, timecnt, &timecnt_alloc);
+	attypes[timecnt].at = starttime;
+	attypes[timecnt].dontmerge = false;
+	attypes[timecnt].type = type;
+	++timecnt;
+}
+
+static int
+addtype(zic_t utoff, char const *abbr, bool isdst, bool ttisstd, bool ttisut)
+{
+	register int	i, j;
+
+	if (! (-1L - 2147483647L <= utoff && utoff <= 2147483647L)) {
+		error(_("UT offset out of range"));
+		exit(EXIT_FAILURE);
+	}
+	if (!want_bloat())
+	  ttisstd = ttisut = false;
+
+	for (j = 0; j < charcnt; ++j)
+		if (strcmp(&chars[j], abbr) == 0)
+			break;
+	if (j == charcnt)
+		newabbr(abbr);
+	else {
+	  /* If there's already an entry, return its index.  */
+	  for (i = 0; i < typecnt; i++)
+	    if (utoff == utoffs[i] && isdst == isdsts[i] && j == desigidx[i]
+		&& ttisstd == ttisstds[i] && ttisut == ttisuts[i])
+	      return i;
+	}
+	/*
+	** There isn't one; add a new one, unless there are already too
+	** many.
+	*/
+	if (typecnt >= TZ_MAX_TYPES) {
+		error(_("too many local time types"));
+		exit(EXIT_FAILURE);
+	}
+	i = typecnt++;
+	utoffs[i] = utoff;
+	isdsts[i] = isdst;
+	ttisstds[i] = ttisstd;
+	ttisuts[i] = ttisut;
+	desigidx[i] = j;
+	return i;
+}
+
+static void
+leapadd(zic_t t, int correction, int rolling)
+{
+	register int i;
+
+	if (TZ_MAX_LEAPS <= leapcnt) {
+		error(_("too many leap seconds"));
+		exit(EXIT_FAILURE);
+	}
+	if (rolling && (lo_time != min_time || hi_time != max_time)) {
+	  error(_("Rolling leap seconds not supported with -r"));
+	  exit(EXIT_FAILURE);
+	}
+	for (i = 0; i < leapcnt; ++i)
+		if (t <= trans[i])
+			break;
+	memmove(&trans[i + 1], &trans[i], (leapcnt - i) * sizeof *trans);
+	memmove(&corr[i + 1], &corr[i], (leapcnt - i) * sizeof *corr);
+	memmove(&roll[i + 1], &roll[i], (leapcnt - i) * sizeof *roll);
+	trans[i] = t;
+	corr[i] = correction;
+	roll[i] = rolling;
+	++leapcnt;
+}
+
+static void
+adjleap(void)
+{
+	register int	i;
+	register zic_t	last = 0;
+	register zic_t	prevtrans = 0;
+
+	/*
+	** propagate leap seconds forward
+	*/
+	for (i = 0; i < leapcnt; ++i) {
+		if (trans[i] - prevtrans < 28 * SECSPERDAY) {
+		  error(_("Leap seconds too close together"));
+		  exit(EXIT_FAILURE);
+		}
+		prevtrans = trans[i];
+		trans[i] = tadd(trans[i], last);
+		last = corr[i] += last;
+	}
+
+	if (0 <= leapexpires) {
+	  leapexpires = oadd(leapexpires, last);
+	  if (! (leapcnt == 0 || (trans[leapcnt - 1] < leapexpires))) {
+	    error(_("last Leap time does not precede Expires time"));
+	    exit(EXIT_FAILURE);
+	  }
+	}
+}
+
+/* Is A a space character in the C locale?  */
+static bool
+is_space(char a)
+{
+	switch (a) {
+	  default:
+		return false;
+	  case ' ': case '\f': case '\n': case '\r': case '\t': case '\v':
+		return true;
+	}
+}
+
+/* Is A an alphabetic character in the C locale?  */
+static bool
+is_alpha(char a)
+{
+	switch (a) {
+	  default:
+		return false;
+	  case 'A': case 'B': case 'C': case 'D': case 'E': case 'F': case 'G':
+	  case 'H': case 'I': case 'J': case 'K': case 'L': case 'M': case 'N':
+	  case 'O': case 'P': case 'Q': case 'R': case 'S': case 'T': case 'U':
+	  case 'V': case 'W': case 'X': case 'Y': case 'Z':
+	  case 'a': case 'b': case 'c': case 'd': case 'e': case 'f': case 'g':
+	  case 'h': case 'i': case 'j': case 'k': case 'l': case 'm': case 'n':
+	  case 'o': case 'p': case 'q': case 'r': case 's': case 't': case 'u':
+	  case 'v': case 'w': case 'x': case 'y': case 'z':
+		return true;
+	}
+}
+
+/* If A is an uppercase character in the C locale, return its lowercase
+   counterpart.  Otherwise, return A.  */
+static char
+lowerit(char a)
+{
+	switch (a) {
+	  default: return a;
+	  case 'A': return 'a'; case 'B': return 'b'; case 'C': return 'c';
+	  case 'D': return 'd'; case 'E': return 'e'; case 'F': return 'f';
+	  case 'G': return 'g'; case 'H': return 'h'; case 'I': return 'i';
+	  case 'J': return 'j'; case 'K': return 'k'; case 'L': return 'l';
+	  case 'M': return 'm'; case 'N': return 'n'; case 'O': return 'o';
+	  case 'P': return 'p'; case 'Q': return 'q'; case 'R': return 'r';
+	  case 'S': return 's'; case 'T': return 't'; case 'U': return 'u';
+	  case 'V': return 'v'; case 'W': return 'w'; case 'X': return 'x';
+	  case 'Y': return 'y'; case 'Z': return 'z';
+	}
+}
+
+/* case-insensitive equality */
+static ATTRIBUTE_REPRODUCIBLE bool
+ciequal(register const char *ap, register const char *bp)
+{
+	while (lowerit(*ap) == lowerit(*bp++))
+		if (*ap++ == '\0')
+			return true;
+	return false;
+}
+
+static ATTRIBUTE_REPRODUCIBLE bool
+itsabbr(register const char *abbr, register const char *word)
+{
+	if (lowerit(*abbr) != lowerit(*word))
+		return false;
+	++word;
+	while (*++abbr != '\0')
+		do {
+			if (*word == '\0')
+				return false;
+		} while (lowerit(*word++) != lowerit(*abbr));
+	return true;
+}
+
+/* Return true if ABBR is an initial prefix of WORD, ignoring ASCII case.  */
+
+static ATTRIBUTE_REPRODUCIBLE bool
+ciprefix(char const *abbr, char const *word)
+{
+  do
+    if (!*abbr)
+      return true;
+  while (lowerit(*abbr++) == lowerit(*word++));
+
+  return false;
+}
+
+static const struct lookup *
+byword(const char *word, const struct lookup *table)
+{
+	register const struct lookup *	foundlp;
+	register const struct lookup *	lp;
+
+	if (word == NULL || table == NULL)
+		return NULL;
+
+	/* If TABLE is LASTS and the word starts with "last" followed
+	   by a non-'-', skip the "last" and look in WDAY_NAMES instead.
+	   Warn about any usage of the undocumented prefix "last-".  */
+	if (table == lasts && ciprefix("last", word) && word[4]) {
+	  if (word[4] == '-')
+	    warning(_("\"%s\" is undocumented; use \"last%s\" instead"),
+		    word, word + 5);
+	  else {
+	    word += 4;
+	    table = wday_names;
+	  }
+	}
+
+	/*
+	** Look for exact match.
+	*/
+	for (lp = table; lp->l_word != NULL; ++lp)
+		if (ciequal(word, lp->l_word))
+			return lp;
+	/*
+	** Look for inexact match.
+	*/
+	foundlp = NULL;
+	for (lp = table; lp->l_word != NULL; ++lp)
+		if (ciprefix(word, lp->l_word)) {
+			if (foundlp == NULL)
+				foundlp = lp;
+			else	return NULL;	/* multiple inexact matches */
+		}
+
+	if (foundlp && noise) {
+	  /* Warn about any backward-compatibility issue with pre-2017c zic.  */
+	  bool pre_2017c_match = false;
+	  for (lp = table; lp->l_word; lp++)
+	    if (itsabbr(word, lp->l_word)) {
+	      if (pre_2017c_match) {
+		warning(_("\"%s\" is ambiguous in pre-2017c zic"), word);
+		break;
+	      }
+	      pre_2017c_match = true;
+	    }
+	}
+
+	return foundlp;
+}
+
+static int
+getfields(char *cp, char **array, int arrayelts)
+{
+	register char *		dp;
+	register int		nsubs;
+
+	nsubs = 0;
+	for ( ; ; ) {
+		char *dstart;
+		while (is_space(*cp))
+				++cp;
+		if (*cp == '\0' || *cp == '#')
+			break;
+		dstart = dp = cp;
+		do {
+			if ((*dp = *cp++) != '"')
+				++dp;
+			else while ((*dp = *cp++) != '"')
+				if (*dp != '\0')
+					++dp;
+				else {
+				  error(_("Odd number of quotation marks"));
+				  exit(EXIT_FAILURE);
+				}
+		} while (*cp && *cp != '#' && !is_space(*cp));
+		if (is_space(*cp))
+			++cp;
+		*dp = '\0';
+		if (nsubs == arrayelts) {
+		  error(_("Too many input fields"));
+		  exit(EXIT_FAILURE);
+		}
+		array[nsubs++] = dstart + (*dstart == '-' && dp == dstart + 1);
+	}
+	return nsubs;
+}
+
+static ATTRIBUTE_NORETURN void
+time_overflow(void)
+{
+  error(_("time overflow"));
+  exit(EXIT_FAILURE);
+}
+
+static ATTRIBUTE_REPRODUCIBLE zic_t
+oadd(zic_t t1, zic_t t2)
+{
+#ifdef ckd_add
+  zic_t sum;
+  if (!ckd_add(&sum, t1, t2))
+    return sum;
+#else
+  if (t1 < 0 ? ZIC_MIN - t1 <= t2 : t2 <= ZIC_MAX - t1)
+    return t1 + t2;
+#endif
+  time_overflow();
+}
+
+static ATTRIBUTE_REPRODUCIBLE zic_t
+tadd(zic_t t1, zic_t t2)
+{
+#ifdef ckd_add
+  zic_t sum;
+  if (!ckd_add(&sum, t1, t2) && min_time <= sum && sum <= max_time)
+    return sum;
+#else
+  if (t1 < 0 ? min_time - t1 <= t2 : t2 <= max_time - t1)
+    return t1 + t2;
+#endif
+  if (t1 == min_time || t1 == max_time)
+    return t1;
+  time_overflow();
+}
+
+/*
+** Given a rule, and a year, compute the date (in seconds since January 1,
+** 1970, 00:00 LOCAL time) in that year that the rule refers to.
+*/
+
+static zic_t
+rpytime(const struct rule *rp, zic_t wantedy)
+{
+	register int	m, i;
+	register zic_t	dayoff;			/* with a nod to Margaret O. */
+	register zic_t	t, y;
+	int yrem;
+
+	if (wantedy == ZIC_MIN)
+		return min_time;
+	if (wantedy == ZIC_MAX)
+		return max_time;
+	m = TM_JANUARY;
+	y = EPOCH_YEAR;
+
+	/* dayoff = floor((wantedy - y) / YEARSPERREPEAT) * DAYSPERREPEAT,
+	   sans overflow.  */
+	yrem = wantedy % YEARSPERREPEAT - y % YEARSPERREPEAT;
+	dayoff = ((wantedy / YEARSPERREPEAT - y / YEARSPERREPEAT
+		   + yrem / YEARSPERREPEAT - (yrem % YEARSPERREPEAT < 0))
+		  * DAYSPERREPEAT);
+	/* wantedy = y + ((wantedy - y) mod YEARSPERREPEAT), sans overflow.  */
+	wantedy = y + (yrem + 2 * YEARSPERREPEAT) % YEARSPERREPEAT;
+
+	while (wantedy != y) {
+		i = len_years[isleap(y)];
+		dayoff = oadd(dayoff, i);
+		y++;
+	}
+	while (m != rp->r_month) {
+		i = len_months[isleap(y)][m];
+		dayoff = oadd(dayoff, i);
+		++m;
+	}
+	i = rp->r_dayofmonth;
+	if (m == TM_FEBRUARY && i == 29 && !isleap(y)) {
+		if (rp->r_dycode == DC_DOWLEQ)
+			--i;
+		else {
+			error(_("use of 2/29 in non leap-year"));
+			exit(EXIT_FAILURE);
+		}
+	}
+	--i;
+	dayoff = oadd(dayoff, i);
+	if (rp->r_dycode == DC_DOWGEQ || rp->r_dycode == DC_DOWLEQ) {
+		/*
+		** Don't trust mod of negative numbers.
+		*/
+		zic_t wday = ((EPOCH_WDAY + dayoff % DAYSPERWEEK + DAYSPERWEEK)
+			      % DAYSPERWEEK);
+		while (wday != rp->r_wday)
+			if (rp->r_dycode == DC_DOWGEQ) {
+				dayoff = oadd(dayoff, 1);
+				if (++wday >= DAYSPERWEEK)
+					wday = 0;
+				++i;
+			} else {
+				dayoff = oadd(dayoff, -1);
+				if (--wday < 0)
+					wday = DAYSPERWEEK - 1;
+				--i;
+			}
+		if (i < 0 || i >= len_months[isleap(y)][m]) {
+			if (noise)
+				warning(_("rule goes past start/end of month; \
+will not work with pre-2004 versions of zic"));
+		}
+	}
+	if (dayoff < min_time / SECSPERDAY)
+		return min_time;
+	if (dayoff > max_time / SECSPERDAY)
+		return max_time;
+	t = (zic_t) dayoff * SECSPERDAY;
+	return tadd(t, rp->r_tod);
+}
+
+static void
+newabbr(const char *string)
+{
+	register int	i;
+
+	if (strcmp(string, GRANDPARENTED) != 0) {
+		register const char *	cp;
+		const char *		mp;
+
+		cp = string;
+		mp = NULL;
+		while (is_alpha(*cp) || ('0' <= *cp && *cp <= '9')
+		       || *cp == '-' || *cp == '+')
+				++cp;
+		if (noise && cp - string < 3)
+		  mp = _("time zone abbreviation has fewer than 3 characters");
+		if (cp - string > ZIC_MAX_ABBR_LEN_WO_WARN)
+		  mp = _("time zone abbreviation has too many characters");
+		if (*cp != '\0')
+mp = _("time zone abbreviation differs from POSIX standard");
+		if (mp != NULL)
+			warning("%s (%s)", mp, string);
+	}
+	i = strlen(string) + 1;
+	if (charcnt + i > TZ_MAX_CHARS) {
+		error(_("too many, or too long, time zone abbreviations"));
+		exit(EXIT_FAILURE);
+	}
+	strcpy(&chars[charcnt], string);
+	charcnt += i;
+}
+
+/* Ensure that the directories of ARGNAME exist, by making any missing
+   ones.  If ANCESTORS, do this only for ARGNAME's ancestors; otherwise,
+   do it for ARGNAME too.  Exit with failure if there is trouble.
+   Do not consider an existing file to be trouble.  */
+static void
+mkdirs(char const *argname, bool ancestors)
+{
+	char *name = estrdup(argname);
+	char *cp = name;
+
+	/* On MS-Windows systems, do not worry about drive letters or
+	   backslashes, as this should suffice in practice.  Time zone
+	   names do not use drive letters and backslashes.  If the -d
+	   option of zic does not name an already-existing directory,
+	   it can use slashes to separate the already-existing
+	   ancestor prefix from the to-be-created subdirectories.  */
+
+	/*
+	 * If -D was specified, do not create directories.  A subsequent
+	 * file operation will fail and produce an appropriate error
+	 * message.
+	 */
+	if (Dflag)
+		return;
+	/* Do not mkdir a root directory, as it must exist.  */
+	while (*cp == '/')
+	  cp++;
+
+	while (cp && ((cp = strchr(cp, '/')) || !ancestors)) {
+		if (cp)
+		  *cp = '\0';
+		/*
+		** Try to create it.  It's OK if creation fails because
+		** the directory already exists, perhaps because some
+		** other process just created it.  For simplicity do
+		** not check first whether it already exists, as that
+		** is checked anyway if the mkdir fails.
+		*/
+		if (mkdir(name, MKDIR_UMASK) != 0) {
+			/* Do not report an error if err == EEXIST, because
+			   some other process might have made the directory
+			   in the meantime.  Likewise for ENOSYS, because
+			   Solaris 10 mkdir fails with ENOSYS if the
+			   directory is an automounted mount point.
+			   Likewise for EACCES, since mkdir can fail
+			   with EACCES merely because the parent directory
+			   is unwritable.  Likewise for most other error
+			   numbers.  */
+			int err = errno;
+			if (err == ELOOP || err == ENAMETOOLONG
+			    || err == ENOENT || err == ENOTDIR) {
+				error(_("%s: Can't create directory %s: %s"),
+				      progname, name, strerror(err));
+				exit(EXIT_FAILURE);
+			}
+		}
+		if (cp)
+		  *cp++ = '/';
+	}
+	free(name);
+}
+
+#include <grp.h>
+#include <pwd.h>
+
+static void
+setgroup(flag, name)
+	gid_t *flag;
+	const char *name;
+{
+	struct group *gr;
+
+	if (*flag != (gid_t)-1) {
+		fprintf(stderr, _("multiple -g flags specified"));
+		exit(EXIT_FAILURE);
+	}
+
+	gr = getgrnam(name);
+	if (gr == 0) {
+		char *ep;
+		unsigned long ul;
+
+		ul = strtoul(name, &ep, 10);
+		if (ul == (unsigned long)(gid_t)ul && *ep == '\0') {
+			*flag = ul;
+			return;
+		}
+		fprintf(stderr, _("group `%s' not found"), name);
+		exit(EXIT_FAILURE);
+	}
+	*flag = gr->gr_gid;
+}
+
+static void
+setuser(flag, name)
+	uid_t *flag;
+	const char *name;
+{
+	struct passwd *pw;
+
+	if (*flag != (gid_t)-1) {
+		fprintf(stderr, _("multiple -u flags specified"));
+		exit(EXIT_FAILURE);
+	}
+
+	pw = getpwnam(name);
+	if (pw == 0) {
+		char *ep;
+		unsigned long ul;
+
+		ul = strtoul(name, &ep, 10);
+		if (ul == (unsigned long)(gid_t)ul && *ep == '\0') {
+			*flag = ul;
+			return;
+		}
+		fprintf(stderr, _("user `%s' not found"), name);
+		exit(EXIT_FAILURE);
+	}
+	*flag = pw->pw_uid;
+}
+
+/*
+** UNIX was a registered trademark of The Open Group in 2003.
+*/
diff --git a/contrib/tzcode/zic/README b/contrib/tzcode/zic/README
deleted file mode 100644
index 5cb701eca276..000000000000
--- a/contrib/tzcode/zic/README
+++ /dev/null
@@ -1,88 +0,0 @@
-@(#)README	8.3
-This file is in the public domain, so clarified as of
-2009-05-17 by Arthur David Olson.
-
-$FreeBSD$
-
-"What time is it?" -- Richard Deacon as The King
-"Any time you want it to be." -- Frank Baxter as The Scientist
-					(from the Bell System film "About Time")
-
-The 1989 update of the time zone package featured
-
-*	POSIXization (including interpretation of POSIX-style TZ environment
-	variables, provided by Guy Harris),
-*	ANSIfication (including versions of "mktime" and "difftime"),
-*	SVIDulation (an "altzone" variable)
-*	MACHination (the "gtime" function)
-*	corrections to some time zone data (including corrections to the rules
-	for Great Britain and New Zealand)
-*	reference data from the United States Naval Observatory for folks who
-	want to do additional time zones
-*	and the 1989 data for Saudi Arabia.
-
-(Since this code will be treated as "part of the implementation" in some places
-and as "part of the application" in others, there's no good way to name
-functions, such as timegm, that are not part of the proposed ANSI C standard;
-such functions have kept their old, underscore-free names in this update.)
-
-And the "dysize" function has disappeared; it was present to allow compilation
-of the "date" command on old BSD systems, and a version of "date" is now
-provided in the package.  The "date" command is not created when you "make all"
-since it may lack options provided by the version distributed with your
-operating system, or may not interact with the system in the same way the
-native version does.
-
-Since POSIX frowns on correct leap second handling, the default behavior of
-the "zic" command (in the absence of a "-L" option) has been changed to omit
-leap second information from its output files.
-
-Here is a recipe for acquiring, building, installing, and testing the
-tz distribution on a GNU/Linux or similar host.
-
-	mkdir tz
-	cd tz
-	wget 'ftp://elsie.nci.nih.gov/pub/tz*.tar.gz'
-	gzip -dc tzcode*.tar.gz | tar -xf -
-	gzip -dc tzdata*.tar.gz | tar -xf -
-
-Be sure to read the comments in "Makefile" and make any changes needed
-to make things right for your system, especially if you are using some
-platform other than GNU/Linux.  Then run the following commands,
-substituting your desired installation directory for "$HOME/tzdir":
-
-	make TOPDIR=$HOME/tzdir install
-	$HOME/tzdir/etc/zdump -v America/Los_Angeles
-
-To use the new functions, use a "-ltz" option when compiling or linking.
-
-Historical local time information has been included here to:
-
-*	provide a compendium of data about the history of civil time
-	that is useful even if the data are not 100% accurate;
-
-*	give an idea of the variety of local time rules that have
-	existed in the past and thus an idea of the variety that may be
-	expected in the future;
-
-*	provide a test of the generality of the local time rule description
-	system.
-
-The information in the time zone data files is by no means authoritative;
-the files currently do not even attempt to cover all time stamps before
-1970, and there are undoubtedly errors even for time stamps since 1970.
-If you know that the rules are different from those in a file, by all means
-feel free to change file (and please send the changed version to
-tz@elsie.nci.nih.gov for use in the future).  Europeans take note!
-
-Thanks to these Timezone Caballeros who've made major contributions to the
-time conversion package:  Keith Bostic; Bob Devine; Paul Eggert; Robert Elz;
-Guy Harris; Mark Horton; John Mackin; and Bradley White.  Thanks also to
-Michael Bloom, Art Neilson, Stephen Prince, John Sovereign, and Frank Wales
-for testing work, and to Gwillim Law for checking local mean time data.
-None of them are responsible for remaining errors.
-
-Look in the ~ftp/pub directory of elsie.nci.nih.gov
-for updated versions of these files.
-
-Please send comments or information to tz@elsie.nci.nih.gov.
diff --git a/contrib/tzcode/zic/Theory b/contrib/tzcode/zic/Theory
deleted file mode 100644
index 752125c95a56..000000000000
--- a/contrib/tzcode/zic/Theory
+++ /dev/null
@@ -1,570 +0,0 @@
-@(#)Theory	8.4
-This file is in the public domain, so clarified as of
-2009-05-17 by Arthur David Olson.
-$FreeBSD$
-
------ Outline -----
-
-	Time and date functions
-	Names of time zone regions
-	Time zone abbreviations
-	Calendrical issues
-	Time and time zones on Mars
-
------ Time and date functions -----
-
-These time and date functions are upwards compatible with POSIX,
-an international standard for UNIX-like systems.
-As of this writing, the current edition of POSIX is:
-
-  Standard for Information technology
-  -- Portable Operating System Interface (POSIX (R))
-  -- System Interfaces
-  IEEE Std 1003.1, 2004 Edition
-  <http://www.opengroup.org/online-pubs?DOC=7999959899>
-  <http://www.opengroup.org/pubs/catalog/t041.htm>
-
-POSIX has the following properties and limitations.
-
-*	In POSIX, time display in a process is controlled by the
-	environment variable TZ.  Unfortunately, the POSIX TZ string takes
-	a form that is hard to describe and is error-prone in practice.
-	Also, POSIX TZ strings can't deal with other (for example, Israeli)
-	daylight saving time rules, or situations where more than two
-	time zone abbreviations are used in an area.
-
-	The POSIX TZ string takes the following form:
-
-		stdoffset[dst[offset],date[/time],date[/time]]
-
-	where:
-
-	std and dst
-		are 3 or more characters specifying the standard
-		and daylight saving time (DST) zone names.
-		Starting with POSIX.1-2001, std and dst may also be
-		in a quoted form like "<UTC+10>"; this allows
-		"+" and "-" in the names.
-	offset
-		is of the form `[-]hh:[mm[:ss]]' and specifies the
-		offset west of UTC.  The default DST offset is one hour
-		ahead of standard time.
-	date[/time],date[/time]
-		specifies the beginning and end of DST.  If this is absent,
-		the system supplies its own rules for DST, and these can
-		differ from year to year; typically US DST rules are used.
-	time
-		takes the form `hh:[mm[:ss]]' and defaults to 02:00.
-	date
-		takes one of the following forms:
-		Jn (1<=n<=365)
-			origin-1 day number not counting February 29
-		n (0<=n<=365)
-			origin-0 day number counting February 29 if present
-		Mm.n.d (0[Sunday]<=d<=6[Saturday], 1<=n<=5, 1<=m<=12)
-			for the dth day of week n of month m of the year,
-			where week 1 is the first week in which day d appears,
-			and `5' stands for the last week in which day d appears
-			(which may be either the 4th or 5th week).
-
-	Here is an example POSIX TZ string, for US Pacific time using rules
-	appropriate from 1987 through 2006:
-
-		TZ='PST8PDT,M4.1.0/02:00,M10.5.0/02:00'
-
-	This POSIX TZ string is hard to remember, and mishandles time stamps
-	before 1987 and after 2006.  With this package you can use this
-	instead:
-
-		TZ='America/Los_Angeles'
-
-*	POSIX does not define the exact meaning of TZ values like "EST5EDT".
-	Typically the current US DST rules are used to interpret such values,
-	but this means that the US DST rules are compiled into each program
-	that does time conversion.  This means that when US time conversion
-	rules change (as in the United States in 1987), all programs that
-	do time conversion must be recompiled to ensure proper results.
-
-*	In POSIX, there's no tamper-proof way for a process to learn the
-	system's best idea of local wall clock.  (This is important for
-	applications that an administrator wants used only at certain times--
-	without regard to whether the user has fiddled the "TZ" environment
-	variable.  While an administrator can "do everything in UTC" to get
-	around the problem, doing so is inconvenient and precludes handling
-	daylight saving time shifts--as might be required to limit phone
-	calls to off-peak hours.)
-
-*	POSIX requires that systems ignore leap seconds.
-
-These are the extensions that have been made to the POSIX functions:
-
-*	The "TZ" environment variable is used in generating the name of a file
-	from which time zone information is read (or is interpreted a la
-	POSIX); "TZ" is no longer constrained to be a three-letter time zone
-	name followed by a number of hours and an optional three-letter
-	daylight time zone name.  The daylight saving time rules to be used
-	for a particular time zone are encoded in the time zone file;
-	the format of the file allows U.S., Australian, and other rules to be
-	encoded, and allows for situations where more than two time zone
-	abbreviations are used.
-
-	It was recognized that allowing the "TZ" environment variable to
-	take on values such as "America/New_York" might cause "old" programs
-	(that expect "TZ" to have a certain form) to operate incorrectly;
-	consideration was given to using some other environment variable
-	(for example, "TIMEZONE") to hold the string used to generate the
-	time zone information file name.  In the end, however, it was decided
-	to continue using "TZ":  it is widely used for time zone purposes;
-	separately maintaining both "TZ" and "TIMEZONE" seemed a nuisance;
-	and systems where "new" forms of "TZ" might cause problems can simply
-	use TZ values such as "EST5EDT" which can be used both by
-	"new" programs (a la POSIX) and "old" programs (as zone names and
-	offsets).
-
-*	To handle places where more than two time zone abbreviations are used,
-	the functions "localtime" and "gmtime" set tzname[tmp->tm_isdst]
-	(where "tmp" is the value the function returns) to the time zone
-	abbreviation to be used.  This differs from POSIX, where the elements
-	of tzname are only changed as a result of calls to tzset.
-
-*	Since the "TZ" environment variable can now be used to control time
-	conversion, the "daylight" and "timezone" variables are no longer
-	needed.  (These variables are defined and set by "tzset"; however, their
-	values will not be used by "localtime.")
-
-*	The "localtime" function has been set up to deliver correct results
-	for near-minimum or near-maximum time_t values.  (A comment in the
-	source code tells how to get compatibly wrong results).
-
-*	A function "tzsetwall" has been added to arrange for the system's
-	best approximation to local wall clock time to be delivered by
-	subsequent calls to "localtime."  Source code for portable
-	applications that "must" run on local wall clock time should call
-	"tzsetwall();" if such code is moved to "old" systems that don't
-	provide tzsetwall, you won't be able to generate an executable program.
-	(These time zone functions also arrange for local wall clock time to be
-	used if tzset is called--directly or indirectly--and there's no "TZ"
-	environment variable; portable applications should not, however, rely
-	on this behavior since it's not the way SVR2 systems behave.)
-
-*	These functions can account for leap seconds, thanks to Bradley White.
-
-Points of interest to folks with other systems:
-
-*	This package is already part of many POSIX-compliant hosts,
-	including BSD, HP, Linux, Network Appliance, SCO, SGI, and Sun.
-	On such hosts, the primary use of this package
-	is to update obsolete time zone rule tables.
-	To do this, you may need to compile the time zone compiler
-	`zic' supplied with this package instead of using the system `zic',
-	since the format of zic's input changed slightly in late 1994,
-	and many vendors still do not support the new input format.
-
-*	The UNIX Version 7 "timezone" function is not present in this package;
-	it's impossible to reliably map timezone's arguments (a "minutes west
-	of GMT" value and a "daylight saving time in effect" flag) to a
-	time zone abbreviation, and we refuse to guess.
-	Programs that in the past used the timezone function may now examine
-	tzname[localtime(&clock)->tm_isdst] to learn the correct time
-	zone abbreviation to use.  Alternatively, use
-	localtime(&clock)->tm_zone if this has been enabled.
-
-*	The 4.2BSD gettimeofday function is not used in this package.
-	This formerly let users obtain the current UTC offset and DST flag,
-	but this functionality was removed in later versions of BSD.
-
-*	In SVR2, time conversion fails for near-minimum or near-maximum
-	time_t values when doing conversions for places that don't use UTC.
-	This package takes care to do these conversions correctly.
-
-The functions that are conditionally compiled if STD_INSPIRED is defined
-should, at this point, be looked on primarily as food for thought.  They are
-not in any sense "standard compatible"--some are not, in fact, specified in
-*any* standard.  They do, however, represent responses of various authors to
-standardization proposals.
-
-Other time conversion proposals, in particular the one developed by folks at
-Hewlett Packard, offer a wider selection of functions that provide capabilities
-beyond those provided here.  The absence of such functions from this package
-is not meant to discourage the development, standardization, or use of such
-functions.  Rather, their absence reflects the decision to make this package
-contain valid extensions to POSIX, to ensure its broad acceptability.  If
-more powerful time conversion functions can be standardized, so much the
-better.
-
-
------ Names of time zone rule files -----
-
-The time zone rule file naming conventions attempt to strike a balance
-among the following goals:
-
- * Uniquely identify every national region where clocks have all
-   agreed since 1970.  This is essential for the intended use: static
-   clocks keeping local civil time.
-
- * Indicate to humans as to where that region is.  This simplifes use.
-
- * Be robust in the presence of political changes.  This reduces the
-   number of updates and backward-compatibility hacks.  For example,
-   names of countries are ordinarily not used, to avoid
-   incompatibilities when countries change their name
-   (e.g. Zaire->Congo) or when locations change countries
-   (e.g. Hong Kong from UK colony to China).
-
- * Be portable to a wide variety of implementations.
-   This promotes use of the technology.
-
- * Use a consistent naming convention over the entire world.
-   This simplifies both use and maintenance.
-
-This naming convention is not intended for use by inexperienced users
-to select TZ values by themselves (though they can of course examine
-and reuse existing settings).  Distributors should provide
-documentation and/or a simple selection interface that explains the
-names; see the 'tzselect' program supplied with this distribution for
-one example.
-
-Names normally have the form AREA/LOCATION, where AREA is the name
-of a continent or ocean, and LOCATION is the name of a specific
-location within that region.  North and South America share the same
-area, `America'.  Typical names are `Africa/Cairo', `America/New_York',
-and `Pacific/Honolulu'.
-
-Here are the general rules used for choosing location names,
-in decreasing order of importance:
-
-	Use only valid POSIX file name components (i.e., the parts of
-		names other than `/').  Within a file name component,
-		use only ASCII letters, `.', `-' and `_'.  Do not use
-		digits, as that might create an ambiguity with POSIX
-		TZ strings.  A file name component must not exceed 14
-		characters or start with `-'.  E.g., prefer `Brunei'
-		to `Bandar_Seri_Begawan'.
-	Include at least one location per time zone rule set per country.
-		One such location is enough.  Use ISO 3166 (see the file
-		iso3166.tab) to help decide whether something is a country.
-		However, uninhabited ISO 3166 regions like Bouvet Island
-		do not need locations, since local time is not defined there.
-	If all the clocks in a country's region have agreed since 1970,
-		don't bother to include more than one location
-		even if subregions' clocks disagreed before 1970.
-		Otherwise these tables would become annoyingly large.
-	If a name is ambiguous, use a less ambiguous alternative;
-		e.g. many cities are named San Jose and Georgetown, so
-		prefer `Costa_Rica' to `San_Jose' and `Guyana' to `Georgetown'.
-	Keep locations compact.  Use cities or small islands, not countries
-		or regions, so that any future time zone changes do not split
-		locations into different time zones.  E.g. prefer `Paris'
-		to `France', since France has had multiple time zones.
-	Use mainstream English spelling, e.g. prefer `Rome' to `Roma', and
-		prefer `Athens' to the true name (which uses Greek letters).
-		The POSIX file name restrictions encourage this rule.
-	Use the most populous among locations in a country's time zone,
-		e.g. prefer `Shanghai' to `Beijing'.  Among locations with
-		similar populations, pick the best-known location,
-		e.g. prefer `Rome' to `Milan'.
-	Use the singular form, e.g. prefer `Canary' to `Canaries'.
-	Omit common suffixes like `_Islands' and `_City', unless that
-		would lead to ambiguity.  E.g. prefer `Cayman' to
-		`Cayman_Islands' and `Guatemala' to `Guatemala_City',
-		but prefer `Mexico_City' to `Mexico' because the country
-		of Mexico has several time zones.
-	Use `_' to represent a space.
-	Omit `.' from abbreviations in names, e.g. prefer `St_Helena'
-		to `St._Helena'.
-	Do not change established names if they only marginally
-		violate the above rules.  For example, don't change
-		the existing name `Rome' to `Milan' merely because
-		Milan's population has grown to be somewhat greater
-		than Rome's.
-	If a name is changed, put its old spelling in the `backward' file.
-
-The file `zone.tab' lists the geographical locations used to name
-time zone rule files.  It is intended to be an exhaustive list
-of canonical names for geographic regions.
-
-Older versions of this package used a different naming scheme,
-and these older names are still supported.
-See the file `backward' for most of these older names
-(e.g. `US/Eastern' instead of `America/New_York').
-The other old-fashioned names still supported are
-`WET', `CET', `MET', `EET' (see the file `europe'),
-and `Factory' (see the file `factory').
-
-
------ Time zone abbreviations -----
-
-When this package is installed, it generates time zone abbreviations
-like `EST' to be compatible with human tradition and POSIX.
-Here are the general rules used for choosing time zone abbreviations,
-in decreasing order of importance:
-
-	Use abbreviations that consist of three or more ASCII letters.
-		Previous editions of this database also used characters like
-		' ' and '?', but these characters have a special meaning to
-		the shell and cause commands like
-			set `date`
-		to have unexpected effects.
-		Previous editions of this rule required upper-case letters,
-		but the Congressman who introduced Chamorro Standard Time
-		preferred "ChST", so the rule has been relaxed.
-
-		This rule guarantees that all abbreviations could have
-		been specified by a POSIX TZ string.  POSIX
-		requires at least three characters for an
-		abbreviation.  POSIX through 2000 says that an abbreviation
-		cannot start with ':', and cannot contain ',', '-',
-		'+', NUL, or a digit.  POSIX from 2001 on changes this
-		rule to say that an abbreviation can contain only '-', '+',
-		and alphanumeric characters from the portable character set
-		in the current locale.  To be portable to both sets of
-		rules, an abbreviation must therefore use only ASCII
-		letters.
-
-	Use abbreviations that are in common use among English-speakers,
-		e.g. `EST' for Eastern Standard Time in North America.
-		We assume that applications translate them to other languages
-		as part of the normal localization process; for example,
-		a French application might translate `EST' to `HNE'.
-
-	For zones whose times are taken from a city's longitude, use the
-		traditional xMT notation, e.g. `PMT' for Paris Mean Time.
-		The only name like this in current use is `GMT'.
-
-	If there is no common English abbreviation, abbreviate the English
-		translation of the usual phrase used by native speakers.
-		If this is not available or is a phrase mentioning the country
-		(e.g. ``Cape Verde Time''), then:
-
-		When a country has a single or principal time zone region,
-			append `T' to the country's ISO	code, e.g. `CVT' for
-			Cape Verde Time.  For summer time append `ST';
-			for double summer time append `DST'; etc.
-		When a country has multiple time zones, take the first three
-			letters of an English place name identifying each zone
-			and then append `T', `ST', etc. as before;
-			e.g. `VLAST' for VLAdivostok Summer Time.
-
-	Use UTC (with time zone abbreviation "zzz") for locations while
-		uninhabited.  The "zzz" mnemonic is that these locations are,
-		in some sense, asleep.
-
-Application writers should note that these abbreviations are ambiguous
-in practice: e.g. `EST' has a different meaning in Australia than
-it does in the United States.  In new applications, it's often better
-to use numeric UTC offsets like `-0500' instead of time zone
-abbreviations like `EST'; this avoids the ambiguity.
-
-
------ Calendrical issues -----
-
-Calendrical issues are a bit out of scope for a time zone database,
-but they indicate the sort of problems that we would run into if we
-extended the time zone database further into the past.  An excellent
-resource in this area is Nachum Dershowitz and Edward M. Reingold,
-<a href="http://emr.cs.iit.edu/home/reingold/calendar-book/third-edition/">
-Calendrical Calculations: Third Edition
-</a>, Cambridge University Press (2008).  Other information and
-sources are given below.  They sometimes disagree.
-
-
-France
-
-Gregorian calendar adopted 1582-12-20.
-French Revolutionary calendar used 1793-11-24 through 1805-12-31,
-and (in Paris only) 1871-05-06 through 1871-05-23.
-
-
-Russia
-
-From Chris Carrier (1996-12-02):
-On 1929-10-01 the Soviet Union instituted an ``Eternal Calendar''
-with 30-day months plus 5 holidays, with a 5-day week.
-On 1931-12-01 it changed to a 6-day week; in 1934 it reverted to the
-Gregorian calendar while retaining the 6-day week; on 1940-06-27 it
-reverted to the 7-day week.  With the 6-day week the usual days
-off were the 6th, 12th, 18th, 24th and 30th of the month.
-(Source: Evitiar Zerubavel, _The Seven Day Circle_)
-
-
-Mark Brader reported a similar story in "The Book of Calendars", edited
-by Frank Parise (1982, Facts on File, ISBN 0-8719-6467-8), page 377.  But:
-
-From: Petteri Sulonen (via Usenet)
-Date: 14 Jan 1999 00:00:00 GMT
-...
-
-If your source is correct, how come documents between 1929 -- 1940 were
-still dated using the conventional, Gregorian calendar?
-
-I can post a scan of a document dated December 1, 1934, signed by
-Yenukidze, the secretary, on behalf of Kalinin, the President of the
-Executive Committee of the Supreme Soviet, if you like.
-
-
-
-Sweden (and Finland)
-
-From: Mark Brader
-<a href="news:1996Jul6.012937.29190@sq.com">
-Subject: Re: Gregorian reform -- a part of locale?
-</a>
-Date: 1996-07-06
-
-In 1700, Denmark made the transition from Julian to Gregorian.  Sweden
-decided to *start* a transition in 1700 as well, but rather than have one of
-those unsightly calendar gaps :-), they simply decreed that the next leap
-year after 1696 would be in 1744 -- putting the whole country on a calendar
-different from both Julian and Gregorian for a period of 40 years.
-
-However, in 1704 something went wrong and the plan was not carried through;
-they did, after all, have a leap year that year.  And one in 1708.  In 1712
-they gave it up and went back to Julian, putting 30 days in February that
-year!...
-
-Then in 1753, Sweden made the transition to Gregorian in the usual manner,
-getting there only 13 years behind the original schedule.
-
-(A previous posting of this story was challenged, and Swedish readers
-produced the following references to support it: "Tiderakning och historia"
-by Natanael Beckman (1924) and "Tid, en bok om tiderakning och
-kalendervasen" by Lars-Olof Lode'n (no date was given).)
-
-
-Grotefend's data
-
-From: "Michael Palmer" [with one obvious typo fixed]
-Subject: Re: Gregorian Calendar (was Re: Another FHC related question
-Newsgroups: soc.genealogy.german
-Date: Tue, 9 Feb 1999 02:32:48 -800
-...
-
-The following is a(n incomplete) listing, arranged chronologically, of
-European states, with the date they converted from the Julian to the
-Gregorian calendar:
-
-04/15 Oct 1582 - Italy (with exceptions), Spain, Portugal, Poland (Roman
-                 Catholics and Danzig only)
-09/20 Dec 1582 - France, Lorraine
-
-21 Dec 1582/
-   01 Jan 1583 - Holland, Brabant, Flanders, Hennegau
-10/21 Feb 1583 - bishopric of Liege (L"uttich)
-13/24 Feb 1583 - bishopric of Augsburg
-04/15 Oct 1583 - electorate of Trier
-05/16 Oct 1583 - Bavaria, bishoprics of Freising, Eichstedt, Regensburg,
-                 Salzburg, Brixen
-13/24 Oct 1583 - Austrian Oberelsass and Breisgau
-20/31 Oct 1583 - bishopric of Basel
-02/13 Nov 1583 - duchy of J"ulich-Berg
-02/13 Nov 1583 - electorate and city of K"oln
-04/15 Nov 1583 - bishopric of W"urzburg
-11/22 Nov 1583 - electorate of Mainz
-16/27 Nov 1583 - bishopric of Strassburg and the margraviate of Baden
-17/28 Nov 1583 - bishopric of M"unster and duchy of Cleve
-14/25 Dec 1583 - Steiermark
-
-06/17 Jan 1584 - Austria and Bohemia
-11/22 Jan 1584 - Luzern, Uri, Schwyz, Zug, Freiburg, Solothurn
-12/23 Jan 1584 - Silesia and the Lausitz
-22 Jan/
-   02 Feb 1584 - Hungary (legally on 21 Oct 1587)
-      Jun 1584 - Unterwalden
-01/12 Jul 1584 - duchy of Westfalen
-
-16/27 Jun 1585 - bishopric of Paderborn
-
-14/25 Dec 1590 - Transylvania
-
-22 Aug/
-   02 Sep 1612 - duchy of Prussia
-
-13/24 Dec 1614 - Pfalz-Neuburg
-
-          1617 - duchy of Kurland (reverted to the Julian calendar in
-                 1796)
-
-          1624 - bishopric of Osnabr"uck
-
-          1630 - bishopric of Minden
-
-15/26 Mar 1631 - bishopric of Hildesheim
-
-          1655 - Kanton Wallis
-
-05/16 Feb 1682 - city of Strassburg
-
-18 Feb/
-   01 Mar 1700 - Protestant Germany (including Swedish possessions in
-                 Germany), Denmark, Norway
-30 Jun/
-   12 Jul 1700 - Gelderland, Zutphen
-10 Nov/
-   12 Dec 1700 - Utrecht, Overijssel
-
-31 Dec 1700/
-   12 Jan 1701 - Friesland, Groningen, Z"urich, Bern, Basel, Geneva,
-                 Turgau, and Schaffhausen
-
-          1724 - Glarus, Appenzell, and the city of St. Gallen
-
-01 Jan 1750    - Pisa and Florence
-
-02/14 Sep 1752 - Great Britain
-
-17 Feb/
-   01 Mar 1753 - Sweden
-
-1760-1812      - Graub"unden
-
-The Russian empire (including Finland and the Baltic states) did not
-convert to the Gregorian calendar until the Soviet revolution of 1917.
-
-Source:  H. Grotefend, _Taschenbuch der Zeitrechnung des deutschen
-Mittelalters und der Neuzeit_, herausgegeben von Dr. O. Grotefend
-(Hannover:  Hahnsche Buchhandlung, 1941), pp. 26-28.
-
-
------ Time and time zones on Mars -----
-
-Some people have adjusted their work schedules to fit Mars time.
-Dozens of special Mars watches were built for Jet Propulsion
-Laboratory workers who kept Mars time during the Mars Exploration
-Rovers mission (2004).  These timepieces look like normal Seikos and
-Citizens but use Mars seconds rather than terrestrial seconds.
-
-A Mars solar day is called a "sol" and has a mean period equal to
-about 24 hours 39 minutes 35.244 seconds in terrestrial time.  It is
-divided into a conventional 24-hour clock, so each Mars second equals
-about 1.02749125 terrestrial seconds.
-
-The prime meridian of Mars goes through the center of the crater
-Airy-0, named in honor of the British astronomer who built the
-Greenwich telescope that defines Earth's prime meridian.  Mean solar
-time on the Mars prime meridian is called Mars Coordinated Time (MTC).
-
-Each landed mission on Mars has adopted a different reference for
-solar time keeping, so there is no real standard for Mars time zones.
-For example, the Mars Exploration Rover project (2004) defined two
-time zones "Local Solar Time A" and "Local Solar Time B" for its two
-missions, each zone designed so that its time equals local true solar
-time at approximately the middle of the nominal mission.  Such a "time
-zone" is not particularly suited for any application other than the
-mission itself.
-
-Many calendars have been proposed for Mars, but none have achieved
-wide acceptance.  Astronomers often use Mars Sol Date (MSD) which is a
-sequential count of Mars solar days elapsed since about 1873-12-29
-12:00 GMT.
-
-The tz database does not currently support Mars time, but it is
-documented here in the hopes that support will be added eventually.
-
-Sources:
-
-Michael Allison and Robert Schmunk,
-"Technical Notes on Mars Solar Time as Adopted by the Mars24 Sunclock"
-<http://www.giss.nasa.gov/tools/mars24/help/notes.html> (2004-07-30).
-
-Jia-Rui Chong, "Workdays Fit for a Martian", Los Angeles Times
-(2004-01-14), pp A1, A20-A21.
diff --git a/contrib/tzcode/zic/ialloc.c b/contrib/tzcode/zic/ialloc.c
deleted file mode 100644
index 1694c2905c74..000000000000
--- a/contrib/tzcode/zic/ialloc.c
+++ /dev/null
@@ -1,91 +0,0 @@
-/*
-** This file is in the public domain, so clarified as of
-** 2006-07-17 by Arthur David Olson.
-*/
-
-#ifndef lint
-#ifndef NOID
-static const char	elsieid[] = "@(#)ialloc.c	8.30";
-#endif /* !defined NOID */
-#endif /* !defined lint */
-
-#ifndef lint
-static const char rcsid[] =
-  "$FreeBSD$";
-#endif /* not lint */
-
-/*LINTLIBRARY*/
-
-#include "private.h"
-
-#define nonzero(n)	(((n) == 0) ? 1 : (n))
-
-char *
-imalloc(n)
-const int	n;
-{
-	return malloc((size_t) nonzero(n));
-}
-
-char *
-icalloc(nelem, elsize)
-int	nelem;
-int	elsize;
-{
-	if (nelem == 0 || elsize == 0)
-		nelem = elsize = 1;
-	return calloc((size_t) nelem, (size_t) elsize);
-}
-
-void *
-irealloc(pointer, size)
-void * const	pointer;
-const int	size;
-{
-	if (pointer == NULL)
-		return imalloc(size);
-	return realloc((void *) pointer, (size_t) nonzero(size));
-}
-
-char *
-icatalloc(old, new)
-char * const		old;
-const char * const	new;
-{
-	register char *	result;
-	register int	oldsize, newsize;
-
-	newsize = (new == NULL) ? 0 : strlen(new);
-	if (old == NULL)
-		oldsize = 0;
-	else if (newsize == 0)
-		return old;
-	else	oldsize = strlen(old);
-	if ((result = irealloc(old, oldsize + newsize + 1)) != NULL)
-		if (new != NULL)
-			(void) strcpy(result + oldsize, new);
-	return result;
-}
-
-char *
-icpyalloc(string)
-const char * const	string;
-{
-	return icatalloc((char *) NULL, string);
-}
-
-void
-ifree(p)
-char * const	p;
-{
-	if (p != NULL)
-		(void) free(p);
-}
-
-void
-icfree(p)
-char * const	p;
-{
-	if (p != NULL)
-		(void) free(p);
-}
diff --git a/contrib/tzcode/zic/private.h b/contrib/tzcode/zic/private.h
deleted file mode 100644
index d00bf9bae140..000000000000
--- a/contrib/tzcode/zic/private.h
+++ /dev/null
@@ -1,272 +0,0 @@
-#ifndef PRIVATE_H
-
-#define PRIVATE_H
-
-/*
-** This file is in the public domain, so clarified as of
-** 1996-06-05 by Arthur David Olson.
-*/
-
-/*
- * FreeBSD modifications: separate libc's privates from zic's.
- * This makes it easier when we need to update one but not the other.
- * I have removed all of the ifdef spaghetti which is not relevant to
- * zic from this file.
- *
- * $FreeBSD$
- */
-
-/*
-** This header is for use ONLY with the time conversion code.
-** There is no guarantee that it will remain unchanged,
-** or that it will remain at all.
-** Do NOT copy it to any system include directory.
-** Thank you!
-*/
-
-/*
-** ID
-*/
-
-#ifndef lint
-#ifndef NOID
-static const char	privatehid[] = "@(#)private.h	8.6";
-#endif /* !defined NOID */
-#endif /* !defined lint */
-
-#define GRANDPARENTED	"Local time zone must be set--use tzsetup"
-
-/*
-** Defaults for preprocessor symbols.
-** You can override these in your C compiler options, e.g. `-DHAVE_ADJTIME=0'.
-*/
-
-#ifndef HAVE_GETTEXT
-#define HAVE_GETTEXT		0
-#endif /* !defined HAVE_GETTEXT */
-
-#ifndef HAVE_SYMLINK
-#define HAVE_SYMLINK		1
-#endif /* !defined HAVE_SYMLINK */
-
-#ifndef HAVE_SYS_STAT_H
-#define HAVE_SYS_STAT_H		1
-#endif /* !defined HAVE_SYS_STAT_H */
-
-#ifndef HAVE_SYS_WAIT_H
-#define HAVE_SYS_WAIT_H		1
-#endif /* !defined HAVE_SYS_WAIT_H */
-
-#ifndef HAVE_UNISTD_H
-#define HAVE_UNISTD_H		1
-#endif /* !defined HAVE_UNISTD_H */
-
-/*
-** Nested includes
-*/
-
-#include "sys/types.h"	/* for time_t */
-#include "stdio.h"
-#include "errno.h"
-#include "string.h"
-#include "limits.h"	/* for CHAR_BIT et al. */
-#include "time.h"
-#include "stdlib.h"
-
-#if HAVE_GETTEXT
-#include "libintl.h"
-#endif /* HAVE_GETTEXT */
-
-#if HAVE_SYS_WAIT_H
-#include <sys/wait.h>	/* for WIFEXITED and WEXITSTATUS */
-#endif /* HAVE_SYS_WAIT_H */
-
-#if HAVE_UNISTD_H
-#include "unistd.h"	/* for F_OK and R_OK, and other POSIX goodness */
-#endif /* HAVE_UNISTD_H */
-
-#ifndef F_OK
-#define F_OK	0
-#endif /* !defined F_OK */
-#ifndef R_OK
-#define R_OK	4
-#endif /* !defined R_OK */
-
-/* Unlike <ctype.h>'s isdigit, this also works if c < 0 | c > UCHAR_MAX. */
-#define is_digit(c) ((unsigned)(c) - '0' <= 9)
-
-/*
-** Define HAVE_STDINT_H's default value here, rather than at the
-** start, since __GLIBC__'s value depends on previously-included
-** files.
-** (glibc 2.1 and later have stdint.h, even with pre-C99 compilers.)
-*/
-#ifndef HAVE_STDINT_H
-#define HAVE_STDINT_H \
-       (199901 <= __STDC_VERSION__ || \
-       2 < (__GLIBC__ + (0 < __GLIBC_MINOR__)))
-#endif /* !defined HAVE_STDINT_H */
-
-#if HAVE_STDINT_H
-#include "stdint.h"
-#endif /* !HAVE_STDINT_H */
-
-#ifndef INT_FAST64_MAX
-/* Pre-C99 GCC compilers define __LONG_LONG_MAX__ instead of LLONG_MAX.  */
-#if defined LLONG_MAX || defined __LONG_LONG_MAX__
-typedef long long      int_fast64_t;
-#else /* ! (defined LLONG_MAX || defined __LONG_LONG_MAX__) */
-#if (LONG_MAX >> 31) < 0xffffffff
-Please use a compiler that supports a 64-bit integer type (or wider);
-you may need to compile with "-DHAVE_STDINT_H".
-#endif /* (LONG_MAX >> 31) < 0xffffffff */
-typedef long           int_fast64_t;
-#endif /* ! (defined LLONG_MAX || defined __LONG_LONG_MAX__) */
-#endif /* !defined INT_FAST64_MAX */
-
-#ifndef INT32_MAX
-#define INT32_MAX 0x7fffffff
-#endif /* !defined INT32_MAX */
-#ifndef INT32_MIN
-#define INT32_MIN (-1 - INT32_MAX)
-#endif /* !defined INT32_MIN */
-
-/*
-** Workarounds for compilers/systems.
- */
-
-/* 
-** Some time.h implementations don't declare asctime_r.
-** Others might define it as a macro.
-** Fix the former without affecting the latter.
- */
-#ifndef asctime_r
-extern char *  asctime_r(struct tm const *, char *);
-#endif
-
-
-
-/*
-** Private function declarations.
-*/
-char *		icalloc (int nelem, int elsize);
-char *		icatalloc (char * old, const char * new);
-char *		icpyalloc (const char * string);
-char *		imalloc (int n);
-void *		irealloc (void * pointer, int size);
-void		icfree (char * pointer);
-void		ifree (char * pointer);
-const char *	scheck (const char *string, const char *format);
-
-/*
-** Finally, some convenience items.
-*/
-
-#ifndef TRUE
-#define TRUE	1
-#endif /* !defined TRUE */
-
-#ifndef FALSE
-#define FALSE	0
-#endif /* !defined FALSE */
-
-#ifndef TYPE_BIT
-#define TYPE_BIT(type)	(sizeof (type) * CHAR_BIT)
-#endif /* !defined TYPE_BIT */
-
-#ifndef TYPE_SIGNED
-#define TYPE_SIGNED(type) (((type) -1) < 0)
-#endif /* !defined TYPE_SIGNED */
-
-/*
-** Since the definition of TYPE_INTEGRAL contains floating point numbers,
-** it cannot be used in preprocessor directives.
-*/
-
-#ifndef TYPE_INTEGRAL
-#define TYPE_INTEGRAL(type) (((type) 0.5) != 0.5)
-#endif /* !defined TYPE_INTEGRAL */
-
-#ifndef INT_STRLEN_MAXIMUM
-/*
-** 302 / 1000 is log10(2.0) rounded up.
-** Subtract one for the sign bit if the type is signed;
-** add one for integer division truncation;
-** add one more for a minus sign if the type is signed.
-*/
-#define INT_STRLEN_MAXIMUM(type) \
-	((TYPE_BIT(type) - TYPE_SIGNED(type)) * 302 / 1000 + \
-	1 + TYPE_SIGNED(type))
-#endif /* !defined INT_STRLEN_MAXIMUM */
-
-/*
-** INITIALIZE(x)
-*/
-
-#ifndef GNUC_or_lint
-#ifdef lint
-#define GNUC_or_lint
-#endif /* defined lint */
-#ifndef lint
-#ifdef __GNUC__
-#define GNUC_or_lint
-#endif /* defined __GNUC__ */
-#endif /* !defined lint */
-#endif /* !defined GNUC_or_lint */
-
-#ifndef INITIALIZE
-#ifdef GNUC_or_lint
-#define INITIALIZE(x)	((x) = 0)
-#endif /* defined GNUC_or_lint */
-#ifndef GNUC_or_lint
-#define INITIALIZE(x)
-#endif /* !defined GNUC_or_lint */
-#endif /* !defined INITIALIZE */
-
-/*
-** For the benefit of GNU folk...
-** `_(MSGID)' uses the current locale's message library string for MSGID.
-** The default is to use gettext if available, and use MSGID otherwise.
-*/
-
-#ifndef _
-#if HAVE_GETTEXT
-#define _(msgid) gettext(msgid)
-#else /* !HAVE_GETTEXT */
-#define _(msgid) msgid
-#endif /* !HAVE_GETTEXT */
-#endif /* !defined _ */
-
-#ifndef TZ_DOMAIN
-#define TZ_DOMAIN "tz"
-#endif /* !defined TZ_DOMAIN */
-
-/*
-** UNIX was a registered trademark of The Open Group in 2003.
-*/
-
-#ifndef YEARSPERREPEAT
-#define YEARSPERREPEAT		400	/* years before a Gregorian repeat */
-#endif /* !defined YEARSPERREPEAT */
-
-/*
-** The Gregorian year averages 365.2425 days, which is 31556952 seconds.
-*/
-
-#ifndef AVGSECSPERYEAR
-#define AVGSECSPERYEAR		31556952L
-#endif /* !defined AVGSECSPERYEAR */
-
-#ifndef SECSPERREPEAT
-#define SECSPERREPEAT		((int_fast64_t) YEARSPERREPEAT * (int_fast64_t) AVGSECSPERYEAR)
-#endif /* !defined SECSPERREPEAT */
-
-#ifndef SECSPERREPEAT_BITS
-#define SECSPERREPEAT_BITS	34	/* ceil(log2(SECSPERREPEAT)) */
-#endif /* !defined SECSPERREPEAT_BITS */
-
-  /*
-  ** UNIX was a registered trademark of The Open Group in 2003.
-  */
-
-#endif /* !defined PRIVATE_H */
diff --git a/contrib/tzcode/zic/scheck.c b/contrib/tzcode/zic/scheck.c
deleted file mode 100644
index abdb4ba5c79b..000000000000
--- a/contrib/tzcode/zic/scheck.c
+++ /dev/null
@@ -1,68 +0,0 @@
-/*
-** This file is in the public domain, so clarified as of
-** 2006-07-17 by Arthur David Olson.
-*/
-
-#ifndef lint
-#ifndef NOID
-static const char	elsieid[] = "@(#)scheck.c	8.19";
-#endif /* !defined lint */
-#endif /* !defined NOID */
-
-#ifndef lint
-static const char rcsid[] =
-  "$FreeBSD$";
-#endif /* not lint */
-
-/*LINTLIBRARY*/
-
-#include "private.h"
-
-const char *
-scheck(string, format)
-const char * const	string;
-const char * const	format;
-{
-	register char *		fbuf;
-	register const char *	fp;
-	register char *		tp;
-	register int		c;
-	register const char *	result;
-	char			dummy;
-
-	result = "";
-	if (string == NULL || format == NULL)
-		return result;
-	fbuf = imalloc((int) (2 * strlen(format) + 4));
-	if (fbuf == NULL)
-		return result;
-	fp = format;
-	tp = fbuf;
-	while ((*tp++ = c = *fp++) != '\0') {
-		if (c != '%')
-			continue;
-		if (*fp == '%') {
-			*tp++ = *fp++;
-			continue;
-		}
-		*tp++ = '*';
-		if (*fp == '*')
-			++fp;
-		while (is_digit(*fp))
-			*tp++ = *fp++;
-		if (*fp == 'l' || *fp == 'h')
-			*tp++ = *fp++;
-		else if (*fp == '[')
-			do *tp++ = *fp++;
-				while (*fp != '\0' && *fp != ']');
-		if ((*tp++ = *fp++) == '\0')
-			break;
-	}
-	*(tp - 1) = '%';
-	*tp++ = 'c';
-	*tp = '\0';
-	if (sscanf(string, fbuf, &dummy) != 1)
-		result = (char *) format;
-	ifree(fbuf);
-	return result;
-}
diff --git a/contrib/tzcode/zic/zdump.8 b/contrib/tzcode/zic/zdump.8
deleted file mode 100644
index 9ac0a03230dd..000000000000
--- a/contrib/tzcode/zic/zdump.8
+++ /dev/null
@@ -1,63 +0,0 @@
-.\"
-.\"	@(#)zdump.8	8.2
-.\" This file is in the public domain, so clarified as of
-.\" 2009-05-17 by Arthur David Olson.
-.\" $FreeBSD$
-.\"
-.Dd June 20, 2004
-.Dt ZDUMP 8
-.Os
-.Sh NAME
-.Nm zdump
-.Nd timezone dumper
-.Sh SYNOPSIS
-.Nm
-.Op Fl -version
-.Op Fl v
-.Op Fl c Ar [loyear,]hiyear
-.Op Ar zonename ...
-.Sh DESCRIPTION
-The
-.Nm
-utility prints the current time in each
-.Ar zonename
-named on the command line.
-.Pp
-The following options are available:
-.Bl -tag -width indent
-.It Fl -version
-Output version information and exit.
-.It Fl v
-For each
-.Ar zonename
-on the command line,
-print the time at the lowest possible time value,
-the time one day after the lowest possible time value,
-the times both one second before and exactly at
-each detected time discontinuity,
-the time at one day less than the highest possible time value,
-and the time at the highest possible time value,
-Each line ends with
-.Em isdst=1
-if the given time is Daylight Saving Time or
-.Em isdst=0
-otherwise.
-.It Fl c Ar loyear,hiyear
-Cut off verbose output near the start of the given year(s).
-By default,
-the program cuts off verbose output near the starts of the years -500 and 2500.
-.El
-.Sh LIMITATIONS
-The
-.Fl v
-option may not be used on systems with floating-point time_t values
-that are neither float nor double.
-.Pp
-Time discontinuities are found by sampling the results returned by localtime
-at twelve-hour intervals.
-This works in all real-world cases;
-one can construct artificial time zones for which this fails.
-.Sh "SEE ALSO"
-.Xr ctime 3 ,
-.Xr tzfile 5 ,
-.Xr zic 8
diff --git a/contrib/tzcode/zic/zdump.c b/contrib/tzcode/zic/zdump.c
deleted file mode 100644
index 01111fec2c99..000000000000
--- a/contrib/tzcode/zic/zdump.c
+++ /dev/null
@@ -1,668 +0,0 @@
-/*
-** This file is in the public domain, so clarified as of
-** 2009-05-17 by Arthur David Olson.
-*/
-
-#ifndef lint
-static const char rcsid[] =
-  "$FreeBSD$";
-static char	elsieid[] = "@(#)zdump.c	8.10";
-#endif /* not lint */
-
-/*
-** This code has been made independent of the rest of the time
-** conversion package to increase confidence in the verification it provides.
-** You can use this code to help in verifying other implementations.
-*/
-
-#include <err.h>
-#include <stdio.h>	/* for stdout, stderr */
-#include <stdlib.h>	/* for exit, malloc, atoi */
-#include <string.h>	/* for strcpy */
-#include <sys/types.h>	/* for time_t */
-#include <time.h>	/* for struct tm */
-#include <unistd.h>
-#include <float.h>	/* for FLT_MAX and DBL_MAX */
-#include <ctype.h>	/* for isalpha et al. */
-#ifndef isascii
-#define isascii(x) 1
-#endif /* !defined isascii */
-
-#ifndef ZDUMP_LO_YEAR
-#define ZDUMP_LO_YEAR	(-500)
-#endif /* !defined ZDUMP_LO_YEAR */
-
-#ifndef ZDUMP_HI_YEAR
-#define ZDUMP_HI_YEAR	2500
-#endif /* !defined ZDUMP_HI_YEAR */
-
-#ifndef MAX_STRING_LENGTH
-#define MAX_STRING_LENGTH	1024
-#endif /* !defined MAX_STRING_LENGTH */
-
-#ifndef TRUE
-#define TRUE		1
-#endif /* !defined TRUE */
-
-#ifndef FALSE
-#define FALSE		0
-#endif /* !defined FALSE */
-
-#ifndef EXIT_SUCCESS
-#define EXIT_SUCCESS	0
-#endif /* !defined EXIT_SUCCESS */
-
-#ifndef EXIT_FAILURE
-#define EXIT_FAILURE	1
-#endif /* !defined EXIT_FAILURE */
-
-#ifndef SECSPERMIN
-#define SECSPERMIN	60
-#endif /* !defined SECSPERMIN */
-
-#ifndef MINSPERHOUR
-#define MINSPERHOUR	60
-#endif /* !defined MINSPERHOUR */
-
-#ifndef SECSPERHOUR
-#define SECSPERHOUR	(SECSPERMIN * MINSPERHOUR)
-#endif /* !defined SECSPERHOUR */
-
-#ifndef HOURSPERDAY
-#define HOURSPERDAY	24
-#endif /* !defined HOURSPERDAY */
-
-#ifndef EPOCH_YEAR
-#define EPOCH_YEAR	1970
-#endif /* !defined EPOCH_YEAR */
-
-#ifndef TM_YEAR_BASE
-#define TM_YEAR_BASE	1900
-#endif /* !defined TM_YEAR_BASE */
-
-#ifndef DAYSPERNYEAR
-#define DAYSPERNYEAR	365
-#endif /* !defined DAYSPERNYEAR */
-
-#ifndef isleap
-#define isleap(y) (((y) % 4) == 0 && (((y) % 100) != 0 || ((y) % 400) == 0))
-#endif /* !defined isleap */
-
-#ifndef isleap_sum
-/*
-** See tzfile.h for details on isleap_sum.
-*/
-#define isleap_sum(a, b)	isleap((a) % 400 + (b) % 400)
-#endif /* !defined isleap_sum */
-
-#define SECSPERDAY	((long) SECSPERHOUR * HOURSPERDAY)
-#define SECSPERNYEAR	(SECSPERDAY * DAYSPERNYEAR)
-#define SECSPERLYEAR	(SECSPERNYEAR + SECSPERDAY)
-
-#ifndef HAVE_GETTEXT
-#define HAVE_GETTEXT 0
-#endif
-#if HAVE_GETTEXT
-#include "locale.h"	/* for setlocale */
-#include "libintl.h"
-#endif /* HAVE_GETTEXT */
-
-#ifndef GNUC_or_lint
-#ifdef lint
-#define GNUC_or_lint
-#else /* !defined lint */
-#ifdef __GNUC__
-#define GNUC_or_lint
-#endif /* defined __GNUC__ */
-#endif /* !defined lint */
-#endif /* !defined GNUC_or_lint */
-
-#ifndef INITIALIZE
-#ifdef GNUC_or_lint
-#define INITIALIZE(x)	((x) = 0)
-#else /* !defined GNUC_or_lint */
-#define INITIALIZE(x)
-#endif /* !defined GNUC_or_lint */
-#endif /* !defined INITIALIZE */
-
-/*
-** For the benefit of GNU folk...
-** `_(MSGID)' uses the current locale's message library string for MSGID.
-** The default is to use gettext if available, and use MSGID otherwise.
-*/
-
-#ifndef _
-#if HAVE_GETTEXT
-#define _(msgid) gettext(msgid)
-#else /* !(HAVE_GETTEXT) */
-#define _(msgid) msgid
-#endif /* !(HAVE_GETTEXT) */
-#endif /* !defined _ */
-
-#ifndef TZ_DOMAIN
-#define TZ_DOMAIN "tz"
-#endif /* !defined TZ_DOMAIN */
-
-extern char **	environ;
-extern char *	tzname[2];
-
-static time_t	absolute_min_time;
-static time_t	absolute_max_time;
-static size_t	longest;
-static char *	progname;
-static int	warned;
-
-static void	usage(FILE *stream, int status);
-static char *	abbr(struct tm * tmp);
-static void	abbrok(const char * abbrp, const char * zone);
-static long	delta(struct tm * newp, struct tm * oldp);
-static void	dumptime(const struct tm * tmp);
-static time_t	hunt(char * name, time_t lot, time_t	hit);
-static void	setabsolutes(void);
-static void	show(char * zone, time_t t, int v);
-static const char *	tformat(void);
-static time_t	yeartot(long y);
-
-#ifndef TYPECHECK
-#define my_localtime	localtime
-#else /* !defined TYPECHECK */
-static struct tm *
-my_localtime(tp)
-time_t *	tp;
-{
-	register struct tm *	tmp;
-
-	tmp = localtime(tp);
-	if (tp != NULL && tmp != NULL) {
-		struct tm	tm;
-		register time_t	t;
-
-		tm = *tmp;
-		t = mktime(&tm);
-		if (t - *tp >= 1 || *tp - t >= 1) {
-			(void) fflush(stdout);
-			(void) fprintf(stderr, "\n%s: ", progname);
-			(void) fprintf(stderr, tformat(), *tp);
-			(void) fprintf(stderr, " ->");
-			(void) fprintf(stderr, " year=%d", tmp->tm_year);
-			(void) fprintf(stderr, " mon=%d", tmp->tm_mon);
-			(void) fprintf(stderr, " mday=%d", tmp->tm_mday);
-			(void) fprintf(stderr, " hour=%d", tmp->tm_hour);
-			(void) fprintf(stderr, " min=%d", tmp->tm_min);
-			(void) fprintf(stderr, " sec=%d", tmp->tm_sec);
-			(void) fprintf(stderr, " isdst=%d", tmp->tm_isdst);
-			(void) fprintf(stderr, " -> ");
-			(void) fprintf(stderr, tformat(), t);
-			(void) fprintf(stderr, "\n");
-		}
-	}
-	return tmp;
-}
-#endif /* !defined TYPECHECK */
-
-static void
-abbrok(abbrp, zone)
-const char * const	abbrp;
-const char * const	zone;
-{
-	register const char *	cp;
-	register char *		wp;
-
-	if (warned)
-		return;
-	cp = abbrp;
-	wp = NULL;
-	while (isascii((unsigned char) *cp) &&
-		(isalnum((unsigned char)*cp) || *cp == '-' || *cp == '+'))
-		++cp;
-	if (cp - abbrp < 3)
-		wp = _("has fewer than 3 characters");
-	else if (cp - abbrp > 6)
-		wp = _("has more than 6 characters");
-	else if (*cp)
-		wp = "has characters other than ASCII alphanumerics, '-' or '+'";
-	else
-		return;
-	(void) fflush(stdout);
-	(void) fprintf(stderr,
-		_("%s: warning: zone \"%s\" abbreviation \"%s\" %s\n"),
-		progname, zone, abbrp, wp);
-	warned = TRUE;
-}
-
-int
-main(argc, argv)
-int	argc;
-char *	argv[];
-{
-	register int		i;
-	register int		c;
-	register int		vflag;
-	register char *		cutarg;
-	register long		cutloyear = ZDUMP_LO_YEAR;
-	register long		cuthiyear = ZDUMP_HI_YEAR;
-	register time_t		cutlotime;
-	register time_t		cuthitime;
-	register char **	fakeenv;
-	time_t			now;
-	time_t			t;
-	time_t			newt;
-	struct tm		tm;
-	struct tm		newtm;
-	register struct tm *	tmp;
-	register struct tm *	newtmp;
-
-	progname=argv[0];
-	INITIALIZE(cutlotime);
-	INITIALIZE(cuthitime);
-#if HAVE_GETTEXT
-	(void) setlocale(LC_MESSAGES, "");
-#ifdef TZ_DOMAINDIR
-	(void) bindtextdomain(TZ_DOMAIN, TZ_DOMAINDIR);
-#endif /* TEXTDOMAINDIR */
-	(void) textdomain(TZ_DOMAIN);
-#endif /* HAVE_GETTEXT */
-	for (i = 1; i < argc; ++i)
-		if (strcmp(argv[i], "--version") == 0) {
-			errx(EXIT_SUCCESS, "%s", elsieid);
-		} else if (strcmp(argv[i], "--help") == 0) {
-			usage(stdout, EXIT_SUCCESS);
-		}
-	vflag = 0;
-	cutarg = NULL;
-	while ((c = getopt(argc, argv, "c:v")) == 'c' || c == 'v')
-		if (c == 'v')
-			vflag = 1;
-		else	cutarg = optarg;
-	if ((c != -1) ||
-		(optind == argc - 1 && strcmp(argv[optind], "=") == 0)) {
-			usage(stderr, EXIT_FAILURE);
-	}
-	if (vflag) {
-		if (cutarg != NULL) {
-			long	lo;
-			long	hi;
-			char	dummy;
-
-			if (sscanf(cutarg, "%ld%c", &hi, &dummy) == 1) {
-				cuthiyear = hi;
-			} else if (sscanf(cutarg, "%ld,%ld%c",
-				&lo, &hi, &dummy) == 2) {
-					cutloyear = lo;
-					cuthiyear = hi;
-			} else {
-(void) fprintf(stderr, _("%s: wild -c argument %s\n"),
-					progname, cutarg);
-				exit(EXIT_FAILURE);
-			}
-		}
-		setabsolutes();
-		cutlotime = yeartot(cutloyear);
-		cuthitime = yeartot(cuthiyear);
-	}
-	(void) time(&now);
-	longest = 0;
-	for (i = optind; i < argc; ++i)
-		if (strlen(argv[i]) > longest)
-			longest = strlen(argv[i]);
-	{
-		register int	from;
-		register int	to;
-
-		for (i = 0;  environ[i] != NULL; ++i)
-			continue;
-		fakeenv = (char **) malloc((size_t) ((i + 2) *
-			sizeof *fakeenv));
-		if (fakeenv == NULL ||
-			(fakeenv[0] = (char *) malloc((size_t) (longest +
-				4))) == NULL)
-					errx(EXIT_FAILURE,
-					     _("malloc() failed"));
-		to = 0;
-		(void) strcpy(fakeenv[to++], "TZ=");
-		for (from = 0; environ[from] != NULL; ++from)
-			if (strncmp(environ[from], "TZ=", 3) != 0)
-				fakeenv[to++] = environ[from];
-		fakeenv[to] = NULL;
-		environ = fakeenv;
-	}
-	for (i = optind; i < argc; ++i) {
-		static char	buf[MAX_STRING_LENGTH];
-
-		(void) strcpy(&fakeenv[0][3], argv[i]);
-		if (!vflag) {
-			show(argv[i], now, FALSE);
-			continue;
-		}
-		warned = FALSE;
-		t = absolute_min_time;
-		show(argv[i], t, TRUE);
-		t += SECSPERHOUR * HOURSPERDAY;
-		show(argv[i], t, TRUE);
-		if (t < cutlotime)
-			t = cutlotime;
-		tmp = my_localtime(&t);
-		if (tmp != NULL) {
-			tm = *tmp;
-			(void) strncpy(buf, abbr(&tm), (sizeof buf) - 1);
-		}
-		for ( ; ; ) {
-			if (t >= cuthitime || t >= cuthitime - SECSPERHOUR * 12)
-				break;
-			newt = t + SECSPERHOUR * 12;
-			newtmp = localtime(&newt);
-			if (newtmp != NULL)
-				newtm = *newtmp;
-			if ((tmp == NULL || newtmp == NULL) ? (tmp != newtmp) :
-				(delta(&newtm, &tm) != (newt - t) ||
-				newtm.tm_isdst != tm.tm_isdst ||
-				strcmp(abbr(&newtm), buf) != 0)) {
-					newt = hunt(argv[i], t, newt);
-					newtmp = localtime(&newt);
-					if (newtmp != NULL) {
-						newtm = *newtmp;
-						(void) strncpy(buf,
-							abbr(&newtm),
-							(sizeof buf) - 1);
-					}
-			}
-			t = newt;
-			tm = newtm;
-			tmp = newtmp;
-		}
-		t = absolute_max_time;
-		t -= SECSPERHOUR * HOURSPERDAY;
-		show(argv[i], t, TRUE);
-		t += SECSPERHOUR * HOURSPERDAY;
-		show(argv[i], t, TRUE);
-	}
-	if (fflush(stdout) || ferror(stdout))
-		errx(EXIT_FAILURE, _("error writing standard output"));
-	exit(EXIT_SUCCESS);
-	/* If exit fails to exit... */
-	return(EXIT_FAILURE);
-}
-
-static void
-setabsolutes(void)
-{
-	if (0.5 == (time_t) 0.5) {
-		/*
-		** time_t is floating.
-		*/
-		if (sizeof (time_t) == sizeof (float)) {
-			absolute_min_time = (time_t) -FLT_MAX;
-			absolute_max_time = (time_t) FLT_MAX;
-		} else if (sizeof (time_t) == sizeof (double)) {
-			absolute_min_time = (time_t) -DBL_MAX;
-			absolute_max_time = (time_t) DBL_MAX;
-		} else {
-			(void) fprintf(stderr,
-_("%s: use of -v on system with floating time_t other than float or double\n"),
-				progname);
-			exit(EXIT_FAILURE);
-		}
-	} else if (0 > (time_t) -1) {
-		/*
-		** time_t is signed.  Assume overflow wraps around.
-		*/
-		time_t t = 0;
-		time_t t1 = 1;
-
-		while (t < t1) {
-			t = t1;
-			t1 = 2 * t1 + 1;
-		}
-
-		absolute_max_time = t;
-		t = -t;
-		absolute_min_time = t - 1;
-		if (t < absolute_min_time)
-			absolute_min_time = t;
-	} else {
-		/*
-		** time_t is unsigned.
-		*/
-		absolute_min_time = 0;
-		absolute_max_time = absolute_min_time - 1;
-	}
-}
-
-static time_t
-yeartot(y)
-const long	y;
-{
-	register long	myy;
-	register long	seconds;
-	register time_t	t;
-
-	myy = EPOCH_YEAR;
-	t = 0;
-	while (myy != y) {
-		if (myy < y) {
-			seconds = isleap(myy) ? SECSPERLYEAR : SECSPERNYEAR;
-			++myy;
-			if (t > absolute_max_time - seconds) {
-				t = absolute_max_time;
-				break;
-			}
-			t += seconds;
-		} else {
-			--myy;
-			seconds = isleap(myy) ? SECSPERLYEAR : SECSPERNYEAR;
-			if (t < absolute_min_time + seconds) {
-				t = absolute_min_time;
-				break;
-			}
-			t -= seconds;
-		}
-	}
-	return t;
-}
-
-static void
-usage(FILE *stream, int status)
-{
-	fprintf(stream,
-_("usage: %s [--version] [-v] [--help] [-c [loyear,]hiyear] zonename ...\n\
-\n\
-Report bugs to tz@elsie.nci.nih.gov.\n"), progname);
-	exit(status);
-}
-
-static time_t
-hunt(char *name, time_t lot, time_t hit)
-{
-	time_t			t;
-	long			diff;
-	struct tm		lotm;
-	register struct tm *	lotmp;
-	struct tm		tm;
-	register struct tm *	tmp;
-	char			loab[MAX_STRING_LENGTH];
-
-	lotmp = my_localtime(&lot);
-	if (lotmp != NULL) {
-		lotm = *lotmp;
-		(void) strncpy(loab, abbr(&lotm), (sizeof loab) - 1);
-	}
-	for ( ; ; ) {
-		diff = (long) (hit - lot);
-		if (diff < 2)
-			break;
-		t = lot;
-		t += diff / 2;
-		if (t <= lot)
-			++t;
-		else if (t >= hit)
-			--t;
-		tmp = my_localtime(&t);
-		if (tmp != NULL)
-			tm = *tmp;
-		if ((lotmp == NULL || tmp == NULL) ? (lotmp == tmp) :
-			(delta(&tm, &lotm) == (t - lot) &&
-			tm.tm_isdst == lotm.tm_isdst &&
-			strcmp(abbr(&tm), loab) == 0)) {
-				lot = t;
-				lotm = tm;
-				lotmp = tmp;
-		} else	hit = t;
-	}
-	show(name, lot, TRUE);
-	show(name, hit, TRUE);
-	return hit;
-}
-
-/*
-** Thanks to Paul Eggert for logic used in delta.
-*/
-
-static long
-delta(newp, oldp)
-struct tm *	newp;
-struct tm *	oldp;
-{
-	register long	result;
-	register int	tmy;
-
-	if (newp->tm_year < oldp->tm_year)
-		return -delta(oldp, newp);
-	result = 0;
-	for (tmy = oldp->tm_year; tmy < newp->tm_year; ++tmy)
-		result += DAYSPERNYEAR + isleap_sum(tmy, TM_YEAR_BASE);
-	result += newp->tm_yday - oldp->tm_yday;
-	result *= HOURSPERDAY;
-	result += newp->tm_hour - oldp->tm_hour;
-	result *= MINSPERHOUR;
-	result += newp->tm_min - oldp->tm_min;
-	result *= SECSPERMIN;
-	result += newp->tm_sec - oldp->tm_sec;
-	return result;
-}
-
-static void
-show(char *zone, time_t t, int v)
-{
-	register struct tm *	tmp;
-
-	(void) printf("%-*s  ", (int) longest, zone);
-	if (v) {
-		tmp = gmtime(&t);
-		if (tmp == NULL) {
-			(void) printf(tformat(), t);
-		} else {
-			dumptime(tmp);
-			(void) printf(" UTC");
-		}
-		(void) printf(" = ");
-	}
-	tmp = my_localtime(&t);
-	dumptime(tmp);
-	if (tmp != NULL) {
-		if (*abbr(tmp) != '\0')
-			(void) printf(" %s", abbr(tmp));
-		if (v) {
-			(void) printf(" isdst=%d", tmp->tm_isdst);
-#ifdef TM_GMTOFF
-			(void) printf(" gmtoff=%ld", tmp->TM_GMTOFF);
-#endif /* defined TM_GMTOFF */
-		}
-	}
-	(void) printf("\n");
-	if (tmp != NULL && *abbr(tmp) != '\0')
-		abbrok(abbr(tmp), zone);
-}
-
-static char *
-abbr(tmp)
-struct tm *	tmp;
-{
-	register char *	result;
-	static char	nada;
-
-	if (tmp->tm_isdst != 0 && tmp->tm_isdst != 1)
-		return &nada;
-	result = tzname[tmp->tm_isdst];
-	return (result == NULL) ? &nada : result;
-}
-
-/*
-** The code below can fail on certain theoretical systems;
-** it works on all known real-world systems as of 2004-12-30.
-*/
-
-static const char *
-tformat(void)
-{
-	if (0.5 == (time_t) 0.5) {	/* floating */
-		if (sizeof (time_t) > sizeof (double))
-			return "%Lg";
-		return "%g";
-	}
-	if (0 > (time_t) -1) {		/* signed */
-		if (sizeof (time_t) > sizeof (long))
-			return "%lld";
-		if (sizeof (time_t) > sizeof (int))
-			return "%ld";
-		return "%d";
-	}
-	if (sizeof (time_t) > sizeof (unsigned long))
-		return "%llu";
-	if (sizeof (time_t) > sizeof (unsigned int))
-		return "%lu";
-	return "%u";
-}
-
-static void
-dumptime(timeptr)
-register const struct tm *	timeptr;
-{
-	static const char	wday_name[][3] = {
-		"Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"
-	};
-	static const char	mon_name[][3] = {
-		"Jan", "Feb", "Mar", "Apr", "May", "Jun",
-		"Jul", "Aug", "Sep", "Oct", "Nov", "Dec"
-	};
-	register const char *	wn;
-	register const char *	mn;
-	register int		lead;
-	register int		trail;
-
-	if (timeptr == NULL) {
-		(void) printf("NULL");
-		return;
-	}
-	/*
-	** The packaged versions of localtime and gmtime never put out-of-range
-	** values in tm_wday or tm_mon, but since this code might be compiled
-	** with other (perhaps experimental) versions, paranoia is in order.
-	*/
-	if (timeptr->tm_wday < 0 || timeptr->tm_wday >=
-		(int) (sizeof wday_name / sizeof wday_name[0]))
-			wn = "???";
-	else		wn = wday_name[timeptr->tm_wday];
-	if (timeptr->tm_mon < 0 || timeptr->tm_mon >=
-		(int) (sizeof mon_name / sizeof mon_name[0]))
-			mn = "???";
-	else		mn = mon_name[timeptr->tm_mon];
-	(void) printf("%.3s %.3s%3d %.2d:%.2d:%.2d ",
-		wn, mn,
-		timeptr->tm_mday, timeptr->tm_hour,
-		timeptr->tm_min, timeptr->tm_sec);
-#define DIVISOR	10
-	trail = timeptr->tm_year % DIVISOR + TM_YEAR_BASE % DIVISOR;
-	lead = timeptr->tm_year / DIVISOR + TM_YEAR_BASE / DIVISOR +
-		trail / DIVISOR;
-	trail %= DIVISOR;
-	if (trail < 0 && lead > 0) {
-		trail += DIVISOR;
-		--lead;
-	} else if (lead < 0 && trail > 0) {
-		trail -= DIVISOR;
-		++lead;
-	}
-	if (lead == 0)
-		(void) printf("%d", trail);
-	else	(void) printf("%d%d", lead, ((trail < 0) ? -trail : trail));
-}
diff --git a/contrib/tzcode/zic/zdump/Makefile b/contrib/tzcode/zic/zdump/Makefile
deleted file mode 100644
index 7ee8db324927..000000000000
--- a/contrib/tzcode/zic/zdump/Makefile
+++ /dev/null
@@ -1,15 +0,0 @@
-# $FreeBSD$
-
-.PATH: ${.CURDIR}/..
-
-PROG=	zdump
-MAN=	zdump.8
-SRCS=	zdump.c ialloc.c scheck.c
-
-CFLAGS+= -DTM_GMTOFF=tm_gmtoff -DTM_ZONE=tm_zone -DSTD_INSPIRED -DPCTS
-CFLAGS+= -DHAVE_LONG_DOUBLE -DTZDIR=\"/usr/share/zoneinfo\" -Demkdir=mkdir
-CFLAGS+= -I${.CURDIR}/.. -I${.CURDIR}/../../../lib/libc/stdtime
-
-WARNS?=	2
-
-.include <bsd.prog.mk>
diff --git a/contrib/tzcode/zic/zic.8 b/contrib/tzcode/zic/zic.8
deleted file mode 100644
index aa191314bfb6..000000000000
--- a/contrib/tzcode/zic/zic.8
+++ /dev/null
@@ -1,468 +0,0 @@
-.\" $FreeBSD$
-.Dd June 20, 2004
-.Dt ZIC 8
-.Os
-.Sh NAME
-.Nm zic
-.Nd timezone compiler
-.Sh SYNOPSIS
-.Nm
-.Op Fl -version
-.Op Fl Dsv
-.Op Fl d Ar directory
-.Op Fl g Ar group
-.Op Fl L Ar leapsecondfilename
-.Op Fl l Ar localtime
-.Op Fl m Ar mode
-.Op Fl p Ar posixrules
-.Op Fl u Ar user
-.Op Fl y Ar command
-.Op Ar filename ...
-.Sh DESCRIPTION
-The
-.Nm
-utility reads text from the file(s) named on the command line
-and creates the time conversion information files specified in this input.
-If a
-.Ar filename
-is
-.Em - ,
-the standard input is read.
-.Pp
-The following options are available:
-.Bl -tag -width indent
-.It Fl -version
-Output version information and exit.
-.It Fl D
-Do not automatically create directories.
-If the input file(s) specify
-an output file in a directory which does not already exist, the
-default behavior is to attempt to create the directory.
-If
-.Fl D
-is specified,
-.Nm
-will instead error out immediately.
-.It Fl d Ar directory
-Create time conversion information files in the named directory rather than
-in the standard directory named below.
-.It Fl g Ar group
-After creating each output file, change its group ownership to the
-specified
-.Ar group
-(which can be either a name or a numeric group ID).
-.It Fl L Ar leapsecondfilename
-Read leap second information from the file with the given name.
-If this option is not used,
-no leap second information appears in output files.
-.It Fl l Ar timezone
-Use the given
-.Ar time zone
-as local time.
-The
-.Nm
-utility will act as if the input contained a link line of the form
-.Pp
-.D1 No "Link	timezone		localtime"
-.Pp
-(Note that this action has no effect on
-.Fx ,
-since the local time zone is specified in
-.Pa /etc/localtime
-and not
-.Pa /usr/share/zoneinfo/localtime . )
-.It Fl m Ar mode
-After creating each output file, change its access mode to
-.Ar mode .
-Both numeric and alphabetic modes are accepted
-(see
-.Xr chmod 1 ) .
-.It Fl p Ar timezone
-Use the given
-.Ar "time zone" Ns 's
-rules when handling POSIX-format
-time zone environment variables.
-The
-.Nm
-utility will act as if the input contained a link line of the form
-.Pp
-.D1 No "Link	timezone		posixrules"
-.It Fl u Ar user
-After creating each output file, change its owner to
-.Ar user
-(which can be either a name or a numeric user ID).
-.It Fl v
-Complain if a year that appears in a data file is outside the range
-of years representable by
-.Xr time 3
-values.
-.It Fl s
-Limit time values stored in output files to values that are the same
-whether they are taken to be signed or unsigned.
-You can use this option to generate SVVS-compatible files.
-.It Fl y Ar command
-Use the given
-.Ar command
-rather than
-.Em yearistype
-when checking year types (see below).
-.El
-.Pp
-Input lines are made up of fields.
-Fields are separated from one another by any number of white space characters.
-Leading and trailing white space on input lines is ignored.
-An unquoted sharp character (#) in the input introduces a comment which extends
-to the end of the line the sharp character appears on.
-White space characters and sharp characters may be enclosed in double quotes
-(") if they are to be used as part of a field.
-Any line that is blank (after comment stripping) is ignored.
-Non-blank lines are expected to be of one of three types:
-rule lines, zone lines, and link lines.
-.Pp
-Names (such as month names) must be in English and are case insensitive.
-Abbreviations, if used, must be unambiguous in context.
-.Pp
-A rule line has the form:
-.Dl "Rule	NAME	FROM	TO	TYPE	IN	ON		AT	SAVE	LETTER/S"
-For example:
-.Dl "Rule	US	1967	1973	\-	Apr	lastSun	2:00	1:00	D"
-.Pp
-The fields that make up a rule line are:
-.Bl -tag -width "LETTER/S" -offset indent
-.It NAME
-Give the (arbitrary) name of the set of rules this rule is part of.
-.It FROM
-Give the first year in which the rule applies.
-Any integer year can be supplied; the Gregorian calendar is assumed.
-The word
-.Em minimum
-(or an abbreviation) means the minimum year representable as an integer.
-The word
-.Em maximum
-(or an abbreviation) means the maximum year representable as an integer.
-Rules can describe times that are not representable as time values,
-with the unrepresentable times ignored; this allows rules to be portable
-among hosts with differing time value types.
-.It TO
-Give the final year in which the rule applies.
-In addition to
-.Em minimum
-and
-.Em maximum
-(as above),
-the word
-.Em only
-(or an abbreviation)
-may be used to repeat the value of the
-.Em FROM
-field.
-.It TYPE
-Give the type of year in which the rule applies.
-If
-.Em TYPE
-is
-.Em \-
-then the rule applies in all years between
-.Em FROM
-and
-.Em TO
-inclusive.
-If
-.Em TYPE
-is something else, then
-.Nm
-executes the command
-.Li yearistype Ar year Ar type
-to check the type of a year:
-an exit status of zero is taken to mean that the year is of the given type;
-an exit status of one is taken to mean that the year is not of the given type.
-.It IN
-Name the month in which the rule takes effect.
-Month names may be abbreviated.
-.It ON
-Give the day on which the rule takes effect.
-Recognized forms include:
-.Pp
-.Bl -tag -width lastSun -compact -offset indent
-.It \&5
-the fifth of the month
-.It lastSun
-the last Sunday in the month
-.It lastMon
-the last Monday in the month
-.It Sun>=8
-first Sunday on or after the eighth
-.It Sun<=25
-last Sunday on or before the 25th
-.El
-.Pp
-Names of days of the week may be abbreviated or spelled out in full.
-Note that there must be no spaces within the
-.Em ON
-field.
-.It AT
-Give the time of day at which the rule takes effect.
-Recognized forms include:
-.Pp
-.Bl -tag -width "\&1:28:14" -offset indent -compact
-.It 2
-time in hours
-.It 2:00
-time in hours and minutes
-.It 15:00
-24-hour format time (for times after noon)
-.It 1:28:14
-time in hours, minutes, and seconds
-.El
-.Pp
-where hour 0 is midnight at the start of the day,
-and hour 24 is midnight at the end of the day.
-Any of these forms may be followed by the letter
-.Sq Li w
-if the given time is local
-.Dq "wall clock"
-time,
-.Sq Li s
-if the given time is local
-.Dq standard
-time, or
-.Sq Li u
-(or
-.Sq Li g
-or
-.Sq Li z )
-if the given time is universal time;
-in the absence of an indicator,
-wall clock time is assumed.
-.It SAVE
-Give the amount of time to be added to local standard time when the rule is in
-effect.
-This field has the same format as the
-.Em AT
-field
-(although, of course, the
-.Sq Li w
-and
-.Sq Li s
-suffixes are not used).
-.It LETTER/S
-Give the
-.Dq "variable part"
-(for example, the
-.Dq S
-or
-.Dq D
-in
-.Dq EST
-or
-.Dq EDT )
-of time zone abbreviations to be used when this rule is in effect.
-If this field is
-.Em \- ,
-the variable part is null.
-.El
-.Pp
-A zone line has the form:
-.Dl "Zone	NAME	GMTOFF	RULES/SAVE	FORMAT	[UNTILYEAR [MONTH [DAY [TIME]]]]"
-For example:
-.Dl "Zone	Australia/Adelaide	9:30	Aus	CST	1971 Oct 31 2:00"
-The fields that make up a zone line are:
-.Bl -tag -width indent
-.It NAME
-The name of the time zone.
-This is the name used in creating the time conversion information file for the
-zone.
-.It GMTOFF
-The amount of time to add to UTC to get standard time in this zone.
-This field has the same format as the
-.Em AT
-and
-.Em SAVE
-fields of rule lines;
-begin the field with a minus sign if time must be subtracted from UTC.
-.It RULES/SAVE
-The name of the rule(s) that apply in the time zone or,
-alternately, an amount of time to add to local standard time.
-If this field is
-.Em \-
-then standard time always applies in the time zone.
-.It FORMAT
-The format for time zone abbreviations in this time zone.
-The pair of characters
-.Em %s
-is used to show where the
-.Dq "variable part"
-of the time zone abbreviation goes.
-Alternately,
-a slash (/)
-separates standard and daylight abbreviations.
-.It UNTILYEAR [MONTH [DAY [TIME]]]
-The time at which the UTC offset or the rule(s) change for a location.
-It is specified as a year, a month, a day, and a time of day.
-If this is specified,
-the time zone information is generated from the given UTC offset
-and rule change until the time specified.
-The month, day, and time of day have the same format as the IN, ON, and AT
-fields of a rule; trailing fields can be omitted, and default to the
-earliest possible value for the missing fields.
-.Pp
-The next line must be a
-.Dq continuation
-line; this has the same form as a zone line except that the
-string
-.Dq Zone
-and the name are omitted, as the continuation line will
-place information starting at the time specified as the
-.Em until
-information in the previous line in the file used by the previous line.
-Continuation lines may contain
-.Em until
-information, just as zone lines do, indicating that the next line is a further
-continuation.
-.El
-.Pp
-A link line has the form
-.Dl "Link	LINK-FROM	LINK-TO"
-For example:
-.Dl "Link	Europe/Istanbul	Asia/Istanbul"
-The
-.Em LINK-FROM
-field should appear as the
-.Em NAME
-field in some zone line;
-the
-.Em LINK-TO
-field is used as an alternate name for that zone.
-.Pp
-Except for continuation lines,
-lines may appear in any order in the input.
-.Pp
-Lines in the file that describes leap seconds have the following form:
-.Dl "Leap	YEAR	MONTH	DAY	HH:MM:SS	CORR	R/S"
-For example:
-.Dl "Leap	1974	Dec	31	23:59:60	+	S"
-The
-.Em YEAR ,
-.Em MONTH ,
-.Em DAY ,
-and
-.Em HH:MM:SS
-fields tell when the leap second happened.
-The
-.Em CORR
-field
-should be
-.Dq +
-if a second was added
-or
-.Dq -
-if a second was skipped.
-.\" There's no need to document the following, since it's impossible for more
-.\" than one leap second to be inserted or deleted at a time.
-.\" The C Standard is in error in suggesting the possibility.
-.\" See Terry J Quinn, The BIPM and the accurate measure of time,
-.\" Proc IEEE 79, 7 (July 1991), 894-905.
-.\"	or
-.\"	.q ++
-.\"	if two seconds were added
-.\"	or
-.\"	.q --
-.\"	if two seconds were skipped.
-The
-.Em R/S
-field
-should be (an abbreviation of)
-.Dq Stationary
-if the leap second time given by the other fields should be interpreted as UTC
-or
-(an abbreviation of)
-.Dq Rolling
-if the leap second time given by the other fields should be interpreted as
-local wall clock time.
-.Sh "EXTENDED EXAMPLE"
-Here is an extended example of
-.Nm
-input, intended to illustrate many of its features.
-.br
-.ne 22
-.nf
-.in +2m
-.ta \w'# Rule\0\0'u +\w'NAME\0\0'u +\w'FROM\0\0'u +\w'1973\0\0'u +\w'TYPE\0\0'u +\w'Apr\0\0'u +\w'lastSun\0\0'u +\w'2:00\0\0'u +\w'SAVE\0\0'u
-.sp
-# Rule	NAME	FROM	TO	TYPE	IN	ON	AT	SAVE	LETTER/S
-Rule	Swiss	1940	only	-	Nov	2	0:00	1:00	S
-Rule	Swiss	1940	only	-	Dec	31	0:00	0	-
-Rule	Swiss	1941	1942	-	May	Sun>=1	2:00	1:00	S
-Rule	Swiss	1941	1942	-	Oct	Sun>=1	0:00	0
-.sp .5
-Rule	EU	1977	1980	-	Apr	Sun>=1	1:00u	1:00	S
-Rule	EU	1977	only	-	Sep	lastSun	1:00u	0	-
-Rule	EU	1978	only	-	Oct	 1	1:00u	0	-
-Rule	EU	1979	1995	-	Sep	lastSun	1:00u	0	-
-Rule	EU	1981	max	-	Mar	lastSun	1:00u	1:00	S
-Rule	EU	1996	max	-	Oct	lastSun	1:00u	0	-
-.sp
-.ta \w'# Zone\0\0'u +\w'Europe/Zurich\0\0'u +\w'0:34:08\0\0'u +\w'RULES/SAVE\0\0'u +\w'FORMAT\0\0'u
-# Zone	NAME	GMTOFF	RULES	FORMAT	UNTIL
-Zone	Europe/Zurich	0:34:08	-	LMT	1848 Sep 12
-		0:29:44	-	BMT	1894 Jun
-		1:00	Swiss	CE%sT	1981
-		1:00	EU	CE%sT
-.sp
-Link	Europe/Zurich	Switzerland
-.sp
-.in
-.fi
-In this example, the zone is named Europe/Zurich but it has an alias
-as Switzerland.
-Zurich was 34 minutes and 8 seconds west of GMT until 1848-09-12
-at 00:00, when the offset changed to 29 minutes and 44 seconds.
-After 1894-06-01 at 00:00 Swiss daylight saving rules (defined with
-lines beginning with "Rule Swiss") apply, and the GMT offset became
-one hour.
-From 1981 to the present, EU daylight saving rules have applied,
-and the UTC offset has remained at one hour.
-.Pp
-In 1940, daylight saving time applied from November 2 at 00:00 to
-December 31 at 00:00.
-In 1941 and 1942, daylight saving time applied from the first Sunday
-in May at 02:00 to the first Sunday in October at 00:00.
-The pre-1981 EU daylight-saving rules have no effect here, but are
-included for completeness.
-Since 1981, daylight saving has begun on the last Sunday in March
-at 01:00 UTC.
-Until 1995 it ended the last Sunday in September at 01:00 UTC, but
-this changed to the last Sunday in October starting in 1996.
-.Pp
-For purposes of display, "LMT" and "BMT" were initially used,
-respectively.
-Since Swiss rules and later EU rules were applied, the display name
-for the timezone has been CET for standard time and CEST for daylight
-saving time.
-.Sh NOTES
-For areas with more than two types of local time,
-you may need to use local standard time in the
-.Em AT
-field of the earliest transition time's rule to ensure that
-the earliest transition time recorded in the compiled file is correct.
-.Pp
-If, for a particular zone, a clock advance caused by the start of
-daylight saving coincides with and is equal to a clock retreat
-caused by a change in UTC offset,
-.Nm
-produces a single transition to daylight saving at the new UTC offset
-(without any change in wall clock time).
-To get separate transitions use multiple zone continuation lines
-specifying transition instants using universal time.
-.Sh FILES
-.Bl -tag -width /usr/share/zoneinfo -compact
-.It /usr/share/zoneinfo
-standard directory used for created files
-.El
-.Sh "SEE ALSO"
-.Xr ctime 3 ,
-.Xr tzfile 5 ,
-.Xr zdump 8
-.\" @(#)zic.8	8.6
-.\" This file is in the public domain, so clarified as of
-.\" 2009-05-17 by Arthur David Olson.
diff --git a/contrib/tzcode/zic/zic.c b/contrib/tzcode/zic/zic.c
deleted file mode 100644
index 00043b7940e7..000000000000
--- a/contrib/tzcode/zic/zic.c
+++ /dev/null
@@ -1,2756 +0,0 @@
-/*
-** This file is in the public domain, so clarified as of
-** 2006-07-17 by Arthur David Olson.
-*/
-
-static const char	elsieid[] = "@(#)zic.c	8.22";
-
-#ifndef lint
-static const char rcsid[] =
-  "$FreeBSD$";
-#endif /* not lint */
-
-#include "private.h"
-#include "tzfile.h"
-#include <err.h>
-#include <locale.h>
-#include <sys/stat.h>			/* for umask manifest constants */
-#include <sys/types.h>
-#include <unistd.h>
-
-#define	ZIC_VERSION	'2'
-
-typedef int_fast64_t	zic_t;
-
-#ifndef ZIC_MAX_ABBR_LEN_WO_WARN
-#define ZIC_MAX_ABBR_LEN_WO_WARN	6
-#endif /* !defined ZIC_MAX_ABBR_LEN_WO_WARN */
-
-#define MKDIR_UMASK (S_IRUSR|S_IWUSR|S_IXUSR|S_IRGRP|S_IXGRP|S_IROTH|S_IXOTH)
-
-/*
-** On some ancient hosts, predicates like `isspace(C)' are defined
-** only if isascii(C) || C == EOF. Modern hosts obey the C Standard,
-** which says they are defined only if C == ((unsigned char) C) || C == EOF.
-** Neither the C Standard nor POSIX require that `isascii' exist.
-** For portability, we check both ancient and modern requirements.
-** If isascii is not defined, the isascii check succeeds trivially.
-*/
-#include "ctype.h"
-#ifndef isascii
-#define isascii(x) 1
-#endif
-
-#define OFFSET_STRLEN_MAXIMUM	(7 + INT_STRLEN_MAXIMUM(long))
-#define RULE_STRLEN_MAXIMUM	8	/* "Mdd.dd.d" */
-
-#define end(cp)	(strchr((cp), '\0'))
-
-struct rule {
-	const char *	r_filename;
-	int		r_linenum;
-	const char *	r_name;
-
-	int		r_loyear;	/* for example, 1986 */
-	int		r_hiyear;	/* for example, 1986 */
-	const char *	r_yrtype;
-	int		r_lowasnum;
-	int		r_hiwasnum;
-
-	int		r_month;	/* 0..11 */
-
-	int		r_dycode;	/* see below */
-	int		r_dayofmonth;
-	int		r_wday;
-
-	long		r_tod;		/* time from midnight */
-	int		r_todisstd;	/* above is standard time if TRUE */
-					/* or wall clock time if FALSE */
-	int		r_todisgmt;	/* above is GMT if TRUE */
-					/* or local time if FALSE */
-	long		r_stdoff;	/* offset from standard time */
-	const char *	r_abbrvar;	/* variable part of abbreviation */
-
-	int		r_todo;		/* a rule to do (used in outzone) */
-	zic_t		r_temp;		/* used in outzone */
-};
-
-/*
-**	r_dycode		r_dayofmonth	r_wday
-*/
-
-#define DC_DOM		0	/* 1..31 */	/* unused */
-#define DC_DOWGEQ	1	/* 1..31 */	/* 0..6 (Sun..Sat) */
-#define DC_DOWLEQ	2	/* 1..31 */	/* 0..6 (Sun..Sat) */
-
-struct zone {
-	const char *	z_filename;
-	int		z_linenum;
-
-	const char *	z_name;
-	long		z_gmtoff;
-	const char *	z_rule;
-	const char *	z_format;
-
-	long		z_stdoff;
-
-	struct rule *	z_rules;
-	int		z_nrules;
-
-	struct rule	z_untilrule;
-	zic_t		z_untiltime;
-};
-
-static void	addtt(zic_t starttime, int type);
-static int	addtype(long gmtoff, const char * abbr, int isdst,
-				int ttisstd, int ttisgmt);
-static void	leapadd(zic_t t, int positive, int rolling, int count);
-static void	adjleap(void);
-static void	associate(void);
-static int	ciequal(const char * ap, const char * bp);
-static void	convert(long val, char * buf);
-static void	convert64(zic_t val, char * buf);
-static void	dolink(const char * fromfield, const char * tofield);
-static void	doabbr(char * abbr, const char * format,
-			const char * letters, int isdst, int doquotes);
-static void	eat(const char * name, int num);
-static void	eats(const char * name, int num,
-			const char * rname, int rnum);
-static long	eitol(int i);
-static void	error(const char * message);
-static char **	getfields(char * buf);
-static long	gethms(const char * string, const char * errstrng,
-			int signable);
-static void	infile(const char * filename);
-static void	inleap(char ** fields, int nfields);
-static void	inlink(char ** fields, int nfields);
-static void	inrule(char ** fields, int nfields);
-static int	inzcont(char ** fields, int nfields);
-static int	inzone(char ** fields, int nfields);
-static int	inzsub(char ** fields, int nfields, int iscont);
-static int	is32(zic_t x);
-static int	itsabbr(const char * abbr, const char * word);
-static int	itsdir(const char * name);
-static int	lowerit(int c);
-static char *	memcheck(char * tocheck);
-static int	mkdirs(char * filename);
-static void	newabbr(const char * abbr);
-static long	oadd(long t1, long t2);
-static void	outzone(const struct zone * zp, int ntzones);
-static void	puttzcode(long code, FILE * fp);
-static void	puttzcode64(zic_t code, FILE * fp);
-static int	rcomp(const void * leftp, const void * rightp);
-static zic_t	rpytime(const struct rule * rp, int wantedy);
-static void	rulesub(struct rule * rp,
-			const char * loyearp, const char * hiyearp,
-			const char * typep, const char * monthp,
-			const char * dayp, const char * timep);
-static int 	stringoffset(char * result, long offset);
-static int	stringrule(char * result, const struct rule * rp,
-			long dstoff, long gmtoff);
-static void 	stringzone(char * result,
-			const struct zone * zp, int ntzones);
-static void	setboundaries(void);
-static void	setgroup(gid_t *flag, const char *name);
-static void	setuser(uid_t *flag, const char *name);
-static zic_t	tadd(zic_t t1, long t2);
-static void	usage(FILE *stream, int status);
-static void	writezone(const char * name, const char * string);
-static int	yearistype(int year, const char * type);
-
-static int		charcnt;
-static int		errors;
-static const char *	filename;
-static int		leapcnt;
-static int		leapseen;
-static int		leapminyear;
-static int		leapmaxyear;
-static int		linenum;
-static int		max_abbrvar_len;
-static int		max_format_len;
-static zic_t		max_time;
-static int		max_year;
-static zic_t		min_time;
-static int		min_year;
-static zic_t		min_time;
-static int		noise;
-static const char *	rfilename;
-static int		rlinenum;
-static int		timecnt;
-static int		typecnt;
-
-/*
-** Line codes.
-*/
-
-#define LC_RULE		0
-#define LC_ZONE		1
-#define LC_LINK		2
-#define LC_LEAP		3
-
-/*
-** Which fields are which on a Zone line.
-*/
-
-#define ZF_NAME		1
-#define ZF_GMTOFF	2
-#define ZF_RULE		3
-#define ZF_FORMAT	4
-#define ZF_TILYEAR	5
-#define ZF_TILMONTH	6
-#define ZF_TILDAY	7
-#define ZF_TILTIME	8
-#define ZONE_MINFIELDS	5
-#define ZONE_MAXFIELDS	9
-
-/*
-** Which fields are which on a Zone continuation line.
-*/
-
-#define ZFC_GMTOFF	0
-#define ZFC_RULE	1
-#define ZFC_FORMAT	2
-#define ZFC_TILYEAR	3
-#define ZFC_TILMONTH	4
-#define ZFC_TILDAY	5
-#define ZFC_TILTIME	6
-#define ZONEC_MINFIELDS	3
-#define ZONEC_MAXFIELDS	7
-
-/*
-** Which files are which on a Rule line.
-*/
-
-#define RF_NAME		1
-#define RF_LOYEAR	2
-#define RF_HIYEAR	3
-#define RF_COMMAND	4
-#define RF_MONTH	5
-#define RF_DAY		6
-#define RF_TOD		7
-#define RF_STDOFF	8
-#define RF_ABBRVAR	9
-#define RULE_FIELDS	10
-
-/*
-** Which fields are which on a Link line.
-*/
-
-#define LF_FROM		1
-#define LF_TO		2
-#define LINK_FIELDS	3
-
-/*
-** Which fields are which on a Leap line.
-*/
-
-#define LP_YEAR		1
-#define LP_MONTH	2
-#define LP_DAY		3
-#define LP_TIME		4
-#define LP_CORR		5
-#define LP_ROLL		6
-#define LEAP_FIELDS	7
-
-/*
-** Year synonyms.
-*/
-
-#define YR_MINIMUM	0
-#define YR_MAXIMUM	1
-#define YR_ONLY		2
-
-static struct rule *	rules;
-static int		nrules;	/* number of rules */
-
-static struct zone *	zones;
-static int		nzones;	/* number of zones */
-
-struct link {
-	const char *	l_filename;
-	int		l_linenum;
-	const char *	l_from;
-	const char *	l_to;
-};
-
-static struct link *	links;
-static int		nlinks;
-
-struct lookup {
-	const char *	l_word;
-	const int	l_value;
-};
-
-static struct lookup const *	byword(const char * string,
-					const struct lookup * lp);
-
-static struct lookup const	line_codes[] = {
-	{ "Rule",	LC_RULE },
-	{ "Zone",	LC_ZONE },
-	{ "Link",	LC_LINK },
-	{ "Leap",	LC_LEAP },
-	{ NULL,		0}
-};
-
-static struct lookup const	mon_names[] = {
-	{ "January",	TM_JANUARY },
-	{ "February",	TM_FEBRUARY },
-	{ "March",	TM_MARCH },
-	{ "April",	TM_APRIL },
-	{ "May",	TM_MAY },
-	{ "June",	TM_JUNE },
-	{ "July",	TM_JULY },
-	{ "August",	TM_AUGUST },
-	{ "September",	TM_SEPTEMBER },
-	{ "October",	TM_OCTOBER },
-	{ "November",	TM_NOVEMBER },
-	{ "December",	TM_DECEMBER },
-	{ NULL,		0 }
-};
-
-static struct lookup const	wday_names[] = {
-	{ "Sunday",	TM_SUNDAY },
-	{ "Monday",	TM_MONDAY },
-	{ "Tuesday",	TM_TUESDAY },
-	{ "Wednesday",	TM_WEDNESDAY },
-	{ "Thursday",	TM_THURSDAY },
-	{ "Friday",	TM_FRIDAY },
-	{ "Saturday",	TM_SATURDAY },
-	{ NULL,		0 }
-};
-
-static struct lookup const	lasts[] = {
-	{ "last-Sunday",	TM_SUNDAY },
-	{ "last-Monday",	TM_MONDAY },
-	{ "last-Tuesday",	TM_TUESDAY },
-	{ "last-Wednesday",	TM_WEDNESDAY },
-	{ "last-Thursday",	TM_THURSDAY },
-	{ "last-Friday",	TM_FRIDAY },
-	{ "last-Saturday",	TM_SATURDAY },
-	{ NULL,			0 }
-};
-
-static struct lookup const	begin_years[] = {
-	{ "minimum",	YR_MINIMUM },
-	{ "maximum",	YR_MAXIMUM },
-	{ NULL,		0 }
-};
-
-static struct lookup const	end_years[] = {
-	{ "minimum",	YR_MINIMUM },
-	{ "maximum",	YR_MAXIMUM },
-	{ "only",	YR_ONLY },
-	{ NULL,		0 }
-};
-
-static struct lookup const	leap_types[] = {
-	{ "Rolling",	TRUE },
-	{ "Stationary",	FALSE },
-	{ NULL,		0 }
-};
-
-static const int	len_months[2][MONSPERYEAR] = {
-	{ 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 },
-	{ 31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 }
-};
-
-static const int	len_years[2] = {
-	DAYSPERNYEAR, DAYSPERLYEAR
-};
-
-static struct attype {
-	zic_t		at;
-	unsigned char	type;
-}			attypes[TZ_MAX_TIMES];
-static long		gmtoffs[TZ_MAX_TYPES];
-static char		isdsts[TZ_MAX_TYPES];
-static unsigned char	abbrinds[TZ_MAX_TYPES];
-static char		ttisstds[TZ_MAX_TYPES];
-static char		ttisgmts[TZ_MAX_TYPES];
-static char		chars[TZ_MAX_CHARS];
-static zic_t		trans[TZ_MAX_LEAPS];
-static long		corr[TZ_MAX_LEAPS];
-static char		roll[TZ_MAX_LEAPS];
-
-/*
-** Memory allocation.
-*/
-
-static char *
-memcheck(ptr)
-char * const	ptr;
-{
-	if (ptr == NULL)
-		errx(EXIT_FAILURE, _("memory exhausted"));
-	return ptr;
-}
-
-#define emalloc(size)		memcheck(imalloc(size))
-#define erealloc(ptr, size)	memcheck(irealloc((ptr), (size)))
-#define ecpyalloc(ptr)		memcheck(icpyalloc(ptr))
-#define ecatalloc(oldp, newp)	memcheck(icatalloc((oldp), (newp)))
-
-/*
-** Error handling.
-*/
-
-static void
-eats(name, num, rname, rnum)
-const char * const	name;
-const int		num;
-const char * const	rname;
-const int		rnum;
-{
-	filename = name;
-	linenum = num;
-	rfilename = rname;
-	rlinenum = rnum;
-}
-
-static void
-eat(name, num)
-const char * const	name;
-const int		num;
-{
-	eats(name, num, (char *) NULL, -1);
-}
-
-static void
-error(string)
-const char * const	string;
-{
-	/*
-	** Match the format of "cc" to allow sh users to
-	**	zic ... 2>&1 | error -t "*" -v
-	** on BSD systems.
-	*/
-	(void) fprintf(stderr, _("\"%s\", line %d: %s"),
-		filename, linenum, string);
-	if (rfilename != NULL)
-		(void) fprintf(stderr, _(" (rule from \"%s\", line %d)"),
-			rfilename, rlinenum);
-	(void) fprintf(stderr, "\n");
-	++errors;
-}
-
-static void
-warning(string)
-const char * const	string;
-{
-	char *	cp;
-
-	cp = ecpyalloc(_("warning: "));
-	cp = ecatalloc(cp, string);
-	error(cp);
-	ifree(cp);
-	--errors;
-}
-
-static void
-usage(FILE *stream, int status)
-  {
-	(void) fprintf(stream, _("usage is zic \
-[ --version ] [--help] [ -v ] [ -l localtime ] [ -p posixrules ] \\\n\
-\t[ -d directory ] [ -L leapseconds ] [ -y yearistype ] [ filename ... ]\n\
-\n\
-Report bugs to tz@elsie.nci.nih.gov.\n"));
-	exit(status);
-}
-
-static const char *	psxrules;
-static const char *	lcltime;
-static const char *	directory;
-static const char *	leapsec;
-static const char *	yitcommand;
-static int		Dflag;
-static uid_t		uflag = (uid_t)-1;
-static gid_t		gflag = (gid_t)-1;
-static mode_t		mflag = (S_IRUSR | S_IRGRP | S_IROTH
-				 | S_IWUSR);
-
-int
-main(argc, argv)
-int	argc;
-char *	argv[];
-{
-	register int	i;
-	register int	j;
-	register int	c;
-
-#ifdef unix
-	(void) umask(umask(S_IWGRP | S_IWOTH) | (S_IWGRP | S_IWOTH));
-#endif /* defined unix */
-#if HAVE_GETTEXT
-	(void) setlocale(LC_ALL, "");
-#ifdef TZ_DOMAINDIR
-	(void) bindtextdomain(TZ_DOMAIN, TZ_DOMAINDIR);
-#endif /* defined TEXTDOMAINDIR */
-	(void) textdomain(TZ_DOMAIN);
-#endif /* HAVE_GETTEXT */
-	if (TYPE_BIT(zic_t) < 64) {
-		(void) fprintf(stderr, "zic: %s\n",
-			_("wild compilation-time specification of zic_t"));
-		exit(EXIT_FAILURE);
-	}
-	for (i = 1; i < argc; ++i)
-		if (strcmp(argv[i], "--version") == 0) {
-			errx(EXIT_SUCCESS, "%s", elsieid);
- 		} else if (strcmp(argv[i], "--help") == 0) {
- 			usage(stdout, EXIT_SUCCESS);
-		}
-	while ((c = getopt(argc, argv, "Dd:g:l:m:p:L:u:vsy:")) != -1)
-		switch (c) {
-			default:
-				usage(stderr, EXIT_FAILURE);
-			case 'D':
-				Dflag = 1;
-				break;
-			case 'd':
-				if (directory == NULL)
-					directory = optarg;
-				else
-					errx(EXIT_FAILURE,
-_("more than one -d option specified"));
-				break;
-			case 'g':
-				setgroup(&gflag, optarg);
-				break;
-			case 'l':
-				if (lcltime == NULL)
-					lcltime = optarg;
-				else
-					errx(EXIT_FAILURE,
-_("more than one -l option specified"));
-				break;
-			case 'm':
-			{
-				void *set = setmode(optarg);
-				if (set == NULL)
-					errx(EXIT_FAILURE,
-_("invalid file mode"));
-				mflag = getmode(set, mflag);
-				free(set);
-				break;
-			}
-			case 'p':
-				if (psxrules == NULL)
-					psxrules = optarg;
-				else
-					errx(EXIT_FAILURE,
-_("more than one -p option specified"));
-				break;
-			case 'u':
-				setuser(&uflag, optarg);
-				break;
-			case 'y':
-				if (yitcommand == NULL)
-					yitcommand = optarg;
-				else
-					errx(EXIT_FAILURE,
-_("more than one -y option specified"));
-				break;
-			case 'L':
-				if (leapsec == NULL)
-					leapsec = optarg;
-				else
-					errx(EXIT_FAILURE,
-_("more than one -L option specified"));
-				break;
-			case 'v':
-				noise = TRUE;
-				break;
-			case 's':
-				(void) printf("zic: -s ignored\n");
-				break;
-		}
-	if (optind == argc - 1 && strcmp(argv[optind], "=") == 0)
-		usage(stderr, EXIT_FAILURE);	/* usage message by request */
-	if (directory == NULL)
-		directory = TZDIR;
-	if (yitcommand == NULL)
-		yitcommand = "yearistype";
-
-	setboundaries();
-
-	if (optind < argc && leapsec != NULL) {
-		infile(leapsec);
-		adjleap();
-	}
-
-	for (i = optind; i < argc; ++i)
-		infile(argv[i]);
-	if (errors)
-		exit(EXIT_FAILURE);
-	associate();
-	for (i = 0; i < nzones; i = j) {
-		/*
-		** Find the next non-continuation zone entry.
-		*/
-		for (j = i + 1; j < nzones && zones[j].z_name == NULL; ++j)
-			continue;
-		outzone(&zones[i], j - i);
-	}
-	/*
-	** Make links.
-	*/
-	for (i = 0; i < nlinks; ++i) {
-		eat(links[i].l_filename, links[i].l_linenum);
-		dolink(links[i].l_from, links[i].l_to);
-		if (noise)
-			for (j = 0; j < nlinks; ++j)
-				if (strcmp(links[i].l_to,
-					links[j].l_from) == 0)
-						warning(_("link to link"));
-	}
-	if (lcltime != NULL) {
-		eat("command line", 1);
-		dolink(lcltime, TZDEFAULT);
-	}
-	if (psxrules != NULL) {
-		eat("command line", 1);
-		dolink(psxrules, TZDEFRULES);
-	}
-	return (errors == 0) ? EXIT_SUCCESS : EXIT_FAILURE;
-}
-
-static void
-dolink(fromfield, tofield)
-const char * const	fromfield;
-const char * const	tofield;
-{
-	register char *	fromname;
-	register char *	toname;
-
-	if (fromfield[0] == '/')
-		fromname = ecpyalloc(fromfield);
-	else {
-		fromname = ecpyalloc(directory);
-		fromname = ecatalloc(fromname, "/");
-		fromname = ecatalloc(fromname, fromfield);
-	}
-	if (tofield[0] == '/')
-		toname = ecpyalloc(tofield);
-	else {
-		toname = ecpyalloc(directory);
-		toname = ecatalloc(toname, "/");
-		toname = ecatalloc(toname, tofield);
-	}
-	/*
-	** We get to be careful here since
-	** there's a fair chance of root running us.
-	*/
-	if (!itsdir(toname))
-		(void) remove(toname);
-	if (link(fromname, toname) != 0) {
-		int	result;
-
-		if (mkdirs(toname) != 0)
-			exit(EXIT_FAILURE);
-
-		result = link(fromname, toname);
-#if HAVE_SYMLINK
-		if (result != 0 &&
-			access(fromname, F_OK) == 0 &&
-			!itsdir(fromname)) {
-				const char *s = tofield;
-				register char * symlinkcontents = NULL;
-				while ((s = strchr(s+1, '/')) != NULL)
-					symlinkcontents =
-						ecatalloc(symlinkcontents,
-						"../");
-				symlinkcontents =
-					ecatalloc(symlinkcontents,
-					fromname);
-				result =
-					symlink(symlinkcontents,
-					toname);
-				if (result == 0)
-warning(_("hard link failed, symbolic link used"));
-				ifree(symlinkcontents);
-		}
-#endif /* HAVE_SYMLINK */
-		if (result != 0) {
-			err(EXIT_FAILURE, _("can't link from %s to %s"),
-			    fromname, toname);
-		}
-	}
-	ifree(fromname);
-	ifree(toname);
-}
-
-#define TIME_T_BITS_IN_FILE	64
-
-static void
-setboundaries (void)
-{
-	register int	i;
-
-	min_time = -1;
-	for (i = 0; i < TIME_T_BITS_IN_FILE - 1; ++i)
-		min_time *= 2;
-	max_time = -(min_time + 1);
-}
-
-static int
-itsdir(name)
-const char * const	name;
-{
-	register char *	myname;
-	register int	accres;
-
-	myname = ecpyalloc(name);
-	myname = ecatalloc(myname, "/.");
-	accres = access(myname, F_OK);
-	ifree(myname);
-	return accres == 0;
-}
-
-/*
-** Associate sets of rules with zones.
-*/
-
-/*
-** Sort by rule name.
-*/
-
-static int
-rcomp(cp1, cp2)
-const void *	cp1;
-const void *	cp2;
-{
-	return strcmp(((const struct rule *) cp1)->r_name,
-		((const struct rule *) cp2)->r_name);
-}
-
-static void
-associate(void)
-{
-	register struct zone *	zp;
-	register struct rule *	rp;
-	register int		base, out;
-	register int		i, j;
-
-	if (nrules != 0) {
-		(void) qsort((void *) rules, (size_t) nrules,
-			(size_t) sizeof *rules, rcomp);
-		for (i = 0; i < nrules - 1; ++i) {
-			if (strcmp(rules[i].r_name,
-				rules[i + 1].r_name) != 0)
-					continue;
-			if (strcmp(rules[i].r_filename,
-				rules[i + 1].r_filename) == 0)
-					continue;
-			eat(rules[i].r_filename, rules[i].r_linenum);
-			warning(_("same rule name in multiple files"));
-			eat(rules[i + 1].r_filename, rules[i + 1].r_linenum);
-			warning(_("same rule name in multiple files"));
-			for (j = i + 2; j < nrules; ++j) {
-				if (strcmp(rules[i].r_name,
-					rules[j].r_name) != 0)
-						break;
-				if (strcmp(rules[i].r_filename,
-					rules[j].r_filename) == 0)
-						continue;
-				if (strcmp(rules[i + 1].r_filename,
-					rules[j].r_filename) == 0)
-						continue;
-				break;
-			}
-			i = j - 1;
-		}
-	}
-	for (i = 0; i < nzones; ++i) {
-		zp = &zones[i];
-		zp->z_rules = NULL;
-		zp->z_nrules = 0;
-	}
-	for (base = 0; base < nrules; base = out) {
-		rp = &rules[base];
-		for (out = base + 1; out < nrules; ++out)
-			if (strcmp(rp->r_name, rules[out].r_name) != 0)
-				break;
-		for (i = 0; i < nzones; ++i) {
-			zp = &zones[i];
-			if (strcmp(zp->z_rule, rp->r_name) != 0)
-				continue;
-			zp->z_rules = rp;
-			zp->z_nrules = out - base;
-		}
-	}
-	for (i = 0; i < nzones; ++i) {
-		zp = &zones[i];
-		if (zp->z_nrules == 0) {
-			/*
-			** Maybe we have a local standard time offset.
-			*/
-			eat(zp->z_filename, zp->z_linenum);
-			zp->z_stdoff = gethms(zp->z_rule, _("unruly zone"),
-				TRUE);
-			/*
-			** Note, though, that if there's no rule,
-			** a '%s' in the format is a bad thing.
-			*/
-			if (strchr(zp->z_format, '%') != 0)
-				error(_("%s in ruleless zone"));
-		}
-	}
-	if (errors)
-		exit(EXIT_FAILURE);
-}
-
-static void
-infile(name)
-const char *	name;
-{
-	register FILE *			fp;
-	register char **		fields;
-	register char *			cp;
-	register const struct lookup *	lp;
-	register int			nfields;
-	register int			wantcont;
-	register int			num;
-	char				buf[BUFSIZ];
-
-	if (strcmp(name, "-") == 0) {
-		name = _("standard input");
-		fp = stdin;
-	} else if ((fp = fopen(name, "r")) == NULL)
-		err(EXIT_FAILURE, _("can't open %s"), name);
-	wantcont = FALSE;
-	for (num = 1; ; ++num) {
-		eat(name, num);
-		if (fgets(buf, (int) sizeof buf, fp) != buf)
-			break;
-		cp = strchr(buf, '\n');
-		if (cp == NULL) {
-			error(_("line too long"));
-			exit(EXIT_FAILURE);
-		}
-		*cp = '\0';
-		fields = getfields(buf);
-		nfields = 0;
-		while (fields[nfields] != NULL) {
-			static char	nada;
-
-			if (strcmp(fields[nfields], "-") == 0)
-				fields[nfields] = &nada;
-			++nfields;
-		}
-		if (nfields == 0) {
-			/* nothing to do */
-		} else if (wantcont) {
-			wantcont = inzcont(fields, nfields);
-		} else {
-			lp = byword(fields[0], line_codes);
-			if (lp == NULL)
-				error(_("input line of unknown type"));
-			else switch ((int) (lp->l_value)) {
-				case LC_RULE:
-					inrule(fields, nfields);
-					wantcont = FALSE;
-					break;
-				case LC_ZONE:
-					wantcont = inzone(fields, nfields);
-					break;
-				case LC_LINK:
-					inlink(fields, nfields);
-					wantcont = FALSE;
-					break;
-				case LC_LEAP:
-					if (name != leapsec)
-						warnx(
-_("leap line in non leap seconds file %s"), name);
-					else	inleap(fields, nfields);
-					wantcont = FALSE;
-					break;
-				default:	/* "cannot happen" */
-					errx(EXIT_FAILURE,
-_("panic: invalid l_value %d"), lp->l_value);
-			}
-		}
-		ifree((char *) fields);
-	}
-	if (ferror(fp))
-		errx(EXIT_FAILURE, _("error reading %s"), filename);
-	if (fp != stdin && fclose(fp))
-		err(EXIT_FAILURE, _("error closing %s"), filename);
-	if (wantcont)
-		error(_("expected continuation line not found"));
-}
-
-/*
-** Convert a string of one of the forms
-**	h	-h	hh:mm	-hh:mm	hh:mm:ss	-hh:mm:ss
-** into a number of seconds.
-** A null string maps to zero.
-** Call error with errstring and return zero on errors.
-*/
-
-static long
-gethms(string, errstring, signable)
-const char *		string;
-const char * const	errstring;
-const int		signable;
-{
-	long	hh;
-	int	mm, ss, sign;
-
-	if (string == NULL || *string == '\0')
-		return 0;
-	if (!signable)
-		sign = 1;
-	else if (*string == '-') {
-		sign = -1;
-		++string;
-	} else	sign = 1;
-	if (sscanf(string, scheck(string, "%ld"), &hh) == 1)
-		mm = ss = 0;
-	else if (sscanf(string, scheck(string, "%ld:%d"), &hh, &mm) == 2)
-		ss = 0;
-	else if (sscanf(string, scheck(string, "%ld:%d:%d"),
-		&hh, &mm, &ss) != 3) {
-			error(errstring);
-			return 0;
-	}
-	if (hh < 0 ||
-		mm < 0 || mm >= MINSPERHOUR ||
-		ss < 0 || ss > SECSPERMIN) {
-			error(errstring);
-			return 0;
-	}
-	if (LONG_MAX / SECSPERHOUR < hh) {
-		error(_("time overflow"));
-		return 0;
-	}
-	if (noise && hh == HOURSPERDAY && mm == 0 && ss == 0)
-		warning(_("24:00 not handled by pre-1998 versions of zic"));
-	if (noise && (hh > HOURSPERDAY ||
-		(hh == HOURSPERDAY && (mm != 0 || ss != 0))))
-warning(_("values over 24 hours not handled by pre-2007 versions of zic"));
-	return oadd(eitol(sign) * hh * eitol(SECSPERHOUR),
-		    eitol(sign) * (eitol(mm) * eitol(SECSPERMIN) + eitol(ss)));
-}
-
-static void
-inrule(fields, nfields)
-register char ** const	fields;
-const int		nfields;
-{
-	static struct rule	r;
-
-	if (nfields != RULE_FIELDS) {
-		error(_("wrong number of fields on Rule line"));
-		return;
-	}
-	if (*fields[RF_NAME] == '\0') {
-		error(_("nameless rule"));
-		return;
-	}
-	r.r_filename = filename;
-	r.r_linenum = linenum;
-	r.r_stdoff = gethms(fields[RF_STDOFF], _("invalid saved time"), TRUE);
-	rulesub(&r, fields[RF_LOYEAR], fields[RF_HIYEAR], fields[RF_COMMAND],
-		fields[RF_MONTH], fields[RF_DAY], fields[RF_TOD]);
-	r.r_name = ecpyalloc(fields[RF_NAME]);
-	r.r_abbrvar = ecpyalloc(fields[RF_ABBRVAR]);
-	if (max_abbrvar_len < strlen(r.r_abbrvar))
-		max_abbrvar_len = strlen(r.r_abbrvar);
-	rules = (struct rule *) (void *) erealloc((char *) rules,
-		(int) ((nrules + 1) * sizeof *rules));
-	rules[nrules++] = r;
-}
-
-static int
-inzone(fields, nfields)
-register char ** const	fields;
-const int		nfields;
-{
-	register int	i;
-	static char *	buf;
-
-	if (nfields < ZONE_MINFIELDS || nfields > ZONE_MAXFIELDS) {
-		error(_("wrong number of fields on Zone line"));
-		return FALSE;
-	}
-	if (strcmp(fields[ZF_NAME], TZDEFAULT) == 0 && lcltime != NULL) {
-		buf = erealloc(buf, (int) (132 + strlen(TZDEFAULT)));
-		(void) sprintf(buf,
-_("\"Zone %s\" line and -l option are mutually exclusive"),
-			TZDEFAULT);
-		error(buf);
-		return FALSE;
-	}
-	if (strcmp(fields[ZF_NAME], TZDEFRULES) == 0 && psxrules != NULL) {
-		buf = erealloc(buf, (int) (132 + strlen(TZDEFRULES)));
-		(void) sprintf(buf,
-_("\"Zone %s\" line and -p option are mutually exclusive"),
-			TZDEFRULES);
-		error(buf);
-		return FALSE;
-	}
-	for (i = 0; i < nzones; ++i)
-		if (zones[i].z_name != NULL &&
-			strcmp(zones[i].z_name, fields[ZF_NAME]) == 0) {
-				buf = erealloc(buf, (int) (132 +
-					strlen(fields[ZF_NAME]) +
-					strlen(zones[i].z_filename)));
-				(void) sprintf(buf,
-_("duplicate zone name %s (file \"%s\", line %d)"),
-					fields[ZF_NAME],
-					zones[i].z_filename,
-					zones[i].z_linenum);
-				error(buf);
-				return FALSE;
-		}
-	return inzsub(fields, nfields, FALSE);
-}
-
-static int
-inzcont(fields, nfields)
-register char ** const	fields;
-const int		nfields;
-{
-	if (nfields < ZONEC_MINFIELDS || nfields > ZONEC_MAXFIELDS) {
-		error(_("wrong number of fields on Zone continuation line"));
-		return FALSE;
-	}
-	return inzsub(fields, nfields, TRUE);
-}
-
-static int
-inzsub(fields, nfields, iscont)
-register char ** const	fields;
-const int		nfields;
-const int		iscont;
-{
-	register char *		cp;
-	static struct zone	z;
-	register int		i_gmtoff, i_rule, i_format;
-	register int		i_untilyear, i_untilmonth;
-	register int		i_untilday, i_untiltime;
-	register int		hasuntil;
-
-	if (iscont) {
-		i_gmtoff = ZFC_GMTOFF;
-		i_rule = ZFC_RULE;
-		i_format = ZFC_FORMAT;
-		i_untilyear = ZFC_TILYEAR;
-		i_untilmonth = ZFC_TILMONTH;
-		i_untilday = ZFC_TILDAY;
-		i_untiltime = ZFC_TILTIME;
-		z.z_name = NULL;
-	} else {
-		i_gmtoff = ZF_GMTOFF;
-		i_rule = ZF_RULE;
-		i_format = ZF_FORMAT;
-		i_untilyear = ZF_TILYEAR;
-		i_untilmonth = ZF_TILMONTH;
-		i_untilday = ZF_TILDAY;
-		i_untiltime = ZF_TILTIME;
-		z.z_name = ecpyalloc(fields[ZF_NAME]);
-	}
-	z.z_filename = filename;
-	z.z_linenum = linenum;
-	z.z_gmtoff = gethms(fields[i_gmtoff], _("invalid UTC offset"), TRUE);
-	if ((cp = strchr(fields[i_format], '%')) != 0) {
-		if (*++cp != 's' || strchr(cp, '%') != 0) {
-			error(_("invalid abbreviation format"));
-			return FALSE;
-		}
-	}
-	z.z_rule = ecpyalloc(fields[i_rule]);
-	z.z_format = ecpyalloc(fields[i_format]);
-	if (max_format_len < strlen(z.z_format))
-		max_format_len = strlen(z.z_format);
-	hasuntil = nfields > i_untilyear;
-	if (hasuntil) {
-		z.z_untilrule.r_filename = filename;
-		z.z_untilrule.r_linenum = linenum;
-		rulesub(&z.z_untilrule,
-			fields[i_untilyear],
-			"only",
-			"",
-			(nfields > i_untilmonth) ?
-			fields[i_untilmonth] : "Jan",
-			(nfields > i_untilday) ? fields[i_untilday] : "1",
-			(nfields > i_untiltime) ? fields[i_untiltime] : "0");
-		z.z_untiltime = rpytime(&z.z_untilrule,
-			z.z_untilrule.r_loyear);
-		if (iscont && nzones > 0 &&
-			z.z_untiltime > min_time &&
-			z.z_untiltime < max_time &&
-			zones[nzones - 1].z_untiltime > min_time &&
-			zones[nzones - 1].z_untiltime < max_time &&
-			zones[nzones - 1].z_untiltime >= z.z_untiltime) {
-				error(_(
-"Zone continuation line end time is not after end time of previous line"
-					));
-				return FALSE;
-		}
-	}
-	zones = (struct zone *) (void *) erealloc((char *) zones,
-		(int) ((nzones + 1) * sizeof *zones));
-	zones[nzones++] = z;
-	/*
-	** If there was an UNTIL field on this line,
-	** there's more information about the zone on the next line.
-	*/
-	return hasuntil;
-}
-
-static void
-inleap(fields, nfields)
-register char ** const	fields;
-const int		nfields;
-{
-	register const char *		cp;
-	register const struct lookup *	lp;
-	register int			i, j;
-	int				year, month, day;
-	long				dayoff, tod;
-	zic_t				t;
-
-	if (nfields != LEAP_FIELDS) {
-		error(_("wrong number of fields on Leap line"));
-		return;
-	}
-	dayoff = 0;
-	cp = fields[LP_YEAR];
-	if (sscanf(cp, scheck(cp, "%d"), &year) != 1) {
-		/*
-		** Leapin' Lizards!
-		*/
-		error(_("invalid leaping year"));
-		return;
-	}
-	if (!leapseen || leapmaxyear < year)
-		leapmaxyear = year;
-	if (!leapseen || leapminyear > year)
-		leapminyear = year;
-	leapseen = TRUE;
-	j = EPOCH_YEAR;
-	while (j != year) {
-		if (year > j) {
-			i = len_years[isleap(j)];
-			++j;
-		} else {
-			--j;
-			i = -len_years[isleap(j)];
-		}
-		dayoff = oadd(dayoff, eitol(i));
-	}
-	if ((lp = byword(fields[LP_MONTH], mon_names)) == NULL) {
-		error(_("invalid month name"));
-		return;
-	}
-	month = lp->l_value;
-	j = TM_JANUARY;
-	while (j != month) {
-		i = len_months[isleap(year)][j];
-		dayoff = oadd(dayoff, eitol(i));
-		++j;
-	}
-	cp = fields[LP_DAY];
-	if (sscanf(cp, scheck(cp, "%d"), &day) != 1 ||
-		day <= 0 || day > len_months[isleap(year)][month]) {
-			error(_("invalid day of month"));
-			return;
-	}
-	dayoff = oadd(dayoff, eitol(day - 1));
-	if (dayoff < 0 && !TYPE_SIGNED(zic_t)) {
-		error(_("time before zero"));
-		return;
-	}
-	if (dayoff < min_time / SECSPERDAY) {
-		error(_("time too small"));
-		return;
-	}
-	if (dayoff > max_time / SECSPERDAY) {
-		error(_("time too large"));
-		return;
-	}
-	t = (zic_t) dayoff * SECSPERDAY;
-	tod = gethms(fields[LP_TIME], _("invalid time of day"), FALSE);
-	cp = fields[LP_CORR];
-	{
-		register int	positive;
-		int		count;
-
-		if (strcmp(cp, "") == 0) { /* infile() turns "-" into "" */
-			positive = FALSE;
-			count = 1;
-		} else if (strcmp(cp, "--") == 0) {
-			positive = FALSE;
-			count = 2;
-		} else if (strcmp(cp, "+") == 0) {
-			positive = TRUE;
-			count = 1;
-		} else if (strcmp(cp, "++") == 0) {
-			positive = TRUE;
-			count = 2;
-		} else {
-			error(_("illegal CORRECTION field on Leap line"));
-			return;
-		}
-		if ((lp = byword(fields[LP_ROLL], leap_types)) == NULL) {
-			error(_(
-				"illegal Rolling/Stationary field on Leap line"
-				));
-			return;
-		}
-		leapadd(tadd(t, tod), positive, lp->l_value, count);
-	}
-}
-
-static void
-inlink(fields, nfields)
-register char ** const	fields;
-const int		nfields;
-{
-	struct link	l;
-
-	if (nfields != LINK_FIELDS) {
-		error(_("wrong number of fields on Link line"));
-		return;
-	}
-	if (*fields[LF_FROM] == '\0') {
-		error(_("blank FROM field on Link line"));
-		return;
-	}
-	if (*fields[LF_TO] == '\0') {
-		error(_("blank TO field on Link line"));
-		return;
-	}
-	l.l_filename = filename;
-	l.l_linenum = linenum;
-	l.l_from = ecpyalloc(fields[LF_FROM]);
-	l.l_to = ecpyalloc(fields[LF_TO]);
-	links = (struct link *) (void *) erealloc((char *) links,
-		(int) ((nlinks + 1) * sizeof *links));
-	links[nlinks++] = l;
-}
-
-static void
-rulesub(rp, loyearp, hiyearp, typep, monthp, dayp, timep)
-register struct rule * const	rp;
-const char * const		loyearp;
-const char * const		hiyearp;
-const char * const		typep;
-const char * const		monthp;
-const char * const		dayp;
-const char * const		timep;
-{
-	register const struct lookup *	lp;
-	register const char *		cp;
-	register char *			dp;
-	register char *			ep;
-
-	if ((lp = byword(monthp, mon_names)) == NULL) {
-		error(_("invalid month name"));
-		return;
-	}
-	rp->r_month = lp->l_value;
-	rp->r_todisstd = FALSE;
-	rp->r_todisgmt = FALSE;
-	dp = ecpyalloc(timep);
-	if (*dp != '\0') {
-		ep = dp + strlen(dp) - 1;
-		switch (lowerit(*ep)) {
-			case 's':	/* Standard */
-				rp->r_todisstd = TRUE;
-				rp->r_todisgmt = FALSE;
-				*ep = '\0';
-				break;
-			case 'w':	/* Wall */
-				rp->r_todisstd = FALSE;
-				rp->r_todisgmt = FALSE;
-				*ep = '\0';
-				break;
-			case 'g':	/* Greenwich */
-			case 'u':	/* Universal */
-			case 'z':	/* Zulu */
-				rp->r_todisstd = TRUE;
-				rp->r_todisgmt = TRUE;
-				*ep = '\0';
-				break;
-		}
-	}
-	rp->r_tod = gethms(dp, _("invalid time of day"), FALSE);
-	ifree(dp);
-	/*
-	** Year work.
-	*/
-	cp = loyearp;
-	lp = byword(cp, begin_years);
-	rp->r_lowasnum = lp == NULL;
-	if (!rp->r_lowasnum) switch ((int) lp->l_value) {
-		case YR_MINIMUM:
-			rp->r_loyear = INT_MIN;
-			break;
-		case YR_MAXIMUM:
-			rp->r_loyear = INT_MAX;
-			break;
-		default:	/* "cannot happen" */
-			errx(EXIT_FAILURE,
-				_("panic: invalid l_value %d"), lp->l_value);
-	} else if (sscanf(cp, scheck(cp, "%d"), &rp->r_loyear) != 1) {
-		error(_("invalid starting year"));
-		return;
-	}
-	cp = hiyearp;
-	lp = byword(cp, end_years);
-	rp->r_hiwasnum = lp == NULL;
-	if (!rp->r_hiwasnum) switch ((int) lp->l_value) {
-		case YR_MINIMUM:
-			rp->r_hiyear = INT_MIN;
-			break;
-		case YR_MAXIMUM:
-			rp->r_hiyear = INT_MAX;
-			break;
-		case YR_ONLY:
-			rp->r_hiyear = rp->r_loyear;
-			break;
-		default:	/* "cannot happen" */
-			errx(EXIT_FAILURE,
-				_("panic: invalid l_value %d"), lp->l_value);
-	} else if (sscanf(cp, scheck(cp, "%d"), &rp->r_hiyear) != 1) {
-		error(_("invalid ending year"));
-		return;
-	}
-	if (rp->r_loyear > rp->r_hiyear) {
-		error(_("starting year greater than ending year"));
-		return;
-	}
-	if (*typep == '\0')
-		rp->r_yrtype = NULL;
-	else {
-		if (rp->r_loyear == rp->r_hiyear) {
-			error(_("typed single year"));
-			return;
-		}
-		rp->r_yrtype = ecpyalloc(typep);
-	}
-	/*
-	** Day work.
-	** Accept things such as:
-	**	1
-	**	last-Sunday
-	**	Sun<=20
-	**	Sun>=7
-	*/
-	dp = ecpyalloc(dayp);
-	if ((lp = byword(dp, lasts)) != NULL) {
-		rp->r_dycode = DC_DOWLEQ;
-		rp->r_wday = lp->l_value;
-		rp->r_dayofmonth = len_months[1][rp->r_month];
-	} else {
-		if ((ep = strchr(dp, '<')) != 0)
-			rp->r_dycode = DC_DOWLEQ;
-		else if ((ep = strchr(dp, '>')) != 0)
-			rp->r_dycode = DC_DOWGEQ;
-		else {
-			ep = dp;
-			rp->r_dycode = DC_DOM;
-		}
-		if (rp->r_dycode != DC_DOM) {
-			*ep++ = 0;
-			if (*ep++ != '=') {
-				error(_("invalid day of month"));
-				ifree(dp);
-				return;
-			}
-			if ((lp = byword(dp, wday_names)) == NULL) {
-				error(_("invalid weekday name"));
-				ifree(dp);
-				return;
-			}
-			rp->r_wday = lp->l_value;
-		}
-		if (sscanf(ep, scheck(ep, "%d"), &rp->r_dayofmonth) != 1 ||
-			rp->r_dayofmonth <= 0 ||
-			(rp->r_dayofmonth > len_months[1][rp->r_month])) {
-				error(_("invalid day of month"));
-				ifree(dp);
-				return;
-		}
-	}
-	ifree(dp);
-}
-
-static void
-convert(val, buf)
-const long	val;
-char * const	buf;
-{
-	register int	i;
-	register int	shift;
-
-	for (i = 0, shift = 24; i < 4; ++i, shift -= 8)
-		buf[i] = val >> shift;
-}
-
-static void
-convert64(val, buf)
-const zic_t	val;
-char * const	buf;
-{
-	register int	i;
-	register int	shift;
-
-	for (i = 0, shift = 56; i < 8; ++i, shift -= 8)
-		buf[i] = val >> shift;
-}
-
-static void
-puttzcode(val, fp)
-const long	val;
-FILE * const	fp;
-{
-	char	buf[4];
-
-	convert(val, buf);
-	(void) fwrite((void *) buf, (size_t) sizeof buf, (size_t) 1, fp);
-}
-
-static void
-puttzcode64(val, fp)
-const zic_t	val;
-FILE * const	fp;
-{
-	char	buf[8];
-
-	convert64(val, buf);
-	(void) fwrite((void *) buf, (size_t) sizeof buf, (size_t) 1, fp);
-}
-
-static int
-atcomp(avp, bvp)
-const void *	avp;
-const void *	bvp;
-{
-	const zic_t	a = ((const struct attype *) avp)->at;
-	const zic_t	b = ((const struct attype *) bvp)->at;
-
-	return (a < b) ? -1 : (a > b);
-}
-
-static int
-is32(x)
-const zic_t	x;
-{
-	return INT32_MIN <= x && x <= INT32_MAX;
-}
-
-static void
-writezone(name, string)
-const char * const	name;
-const char * const	string;
-{
-	register FILE *			fp;
-	register int			i, j;
-	register int			leapcnt32, leapi32;
-	register int			timecnt32, timei32;
-	register int			pass;
-	static char *			fullname;
-	static const struct tzhead	tzh0;
-	static struct tzhead		tzh;
-	zic_t				ats[TZ_MAX_TIMES];
-	unsigned char			types[TZ_MAX_TIMES];
-
-	/*
-	** Sort.
-	*/
-	if (timecnt > 1)
-		(void) qsort((void *) attypes, (size_t) timecnt,
-			(size_t) sizeof *attypes, atcomp);
-	/*
-	** Optimize.
-	*/
-	{
-		int	fromi;
-		int	toi;
-
-		toi = 0;
-		fromi = 0;
-		while (fromi < timecnt && attypes[fromi].at < min_time)
-			++fromi;
-		if (isdsts[0] == 0)
-			while (fromi < timecnt && attypes[fromi].type == 0)
-				++fromi;	/* handled by default rule */
-		for ( ; fromi < timecnt; ++fromi) {
-			if (toi != 0 && ((attypes[fromi].at +
-				gmtoffs[attypes[toi - 1].type]) <=
-				(attypes[toi - 1].at + gmtoffs[toi == 1 ? 0
-				: attypes[toi - 2].type]))) {
-					attypes[toi - 1].type =
-						attypes[fromi].type;
-					continue;
-			}
-			if (toi == 0 ||
-				attypes[toi - 1].type != attypes[fromi].type)
-					attypes[toi++] = attypes[fromi];
-		}
-		timecnt = toi;
-	}
-	/*
-	** Transfer.
-	*/
-	for (i = 0; i < timecnt; ++i) {
-		ats[i] = attypes[i].at;
-		types[i] = attypes[i].type;
-	}
-	/*
-	** Correct for leap seconds.
-	*/
-	for (i = 0; i < timecnt; ++i) {
-		j = leapcnt;
-		while (--j >= 0)
-			if (ats[i] > trans[j] - corr[j]) {
-				ats[i] = tadd(ats[i], corr[j]);
-				break;
-			}
-	}
-	/*
-	** Figure out 32-bit-limited starts and counts.
-	*/
-	timecnt32 = timecnt;
-	timei32 = 0;
-	leapcnt32 = leapcnt;
-	leapi32 = 0;
-	while (timecnt32 > 0 && !is32(ats[timecnt32 - 1]))
-		--timecnt32;
-	while (timecnt32 > 0 && !is32(ats[timei32])) {
-		--timecnt32;
-		++timei32;
-	}
-	while (leapcnt32 > 0 && !is32(trans[leapcnt32 - 1]))
-		--leapcnt32;
-	while (leapcnt32 > 0 && !is32(trans[leapi32])) {
-		--leapcnt32;
-		++leapi32;
-	}
-	fullname = erealloc(fullname,
-		(int) (strlen(directory) + 1 + strlen(name) + 1));
-	(void) sprintf(fullname, "%s/%s", directory, name);
-
-	/*
-	 * Remove old file, if any, to snap links.
-	 */
-	if (!itsdir(fullname) && remove(fullname) != 0 && errno != ENOENT)
-		err(EXIT_FAILURE, _("can't remove %s"), fullname);
-
-	if ((fp = fopen(fullname, "wb")) == NULL) {
-		if (mkdirs(fullname) != 0)
-			exit(EXIT_FAILURE);
-		if ((fp = fopen(fullname, "wb")) == NULL)
-			err(EXIT_FAILURE, _("can't create %s"), fullname);
-	}
-	for (pass = 1; pass <= 2; ++pass) {
-		register int	thistimei, thistimecnt;
-		register int	thisleapi, thisleapcnt;
-		register int	thistimelim, thisleaplim;
-		int		writetype[TZ_MAX_TIMES];
-		int		typemap[TZ_MAX_TYPES];
-		register int	thistypecnt;
-		char		thischars[TZ_MAX_CHARS];
-		char		thischarcnt;
-		int 		indmap[TZ_MAX_CHARS];
-
-		if (pass == 1) {
-			thistimei = timei32;
-			thistimecnt = timecnt32;
-			thisleapi = leapi32;
-			thisleapcnt = leapcnt32;
-		} else {
-			thistimei = 0;
-			thistimecnt = timecnt;
-			thisleapi = 0;
-			thisleapcnt = leapcnt;
-		}
-		thistimelim = thistimei + thistimecnt;
-		thisleaplim = thisleapi + thisleapcnt;
-		for (i = 0; i < typecnt; ++i)
-			writetype[i] = thistimecnt == timecnt;
-		if (thistimecnt == 0) {
-			/*
-			** No transition times fall in the current
-			** (32- or 64-bit) window.
-			*/
-			if (typecnt != 0)
-				writetype[typecnt - 1] = TRUE;
-		} else {
-			for (i = thistimei - 1; i < thistimelim; ++i)
-				if (i >= 0)
-					writetype[types[i]] = TRUE;
-			/*
-			** For America/Godthab and Antarctica/Palmer
-			*/
-			if (thistimei == 0)
-				writetype[0] = TRUE;
-		}
-#ifndef LEAVE_SOME_PRE_2011_SYSTEMS_IN_THE_LURCH
-		/*
-		** For some pre-2011 systems: if the last-to-be-written
-		** standard (or daylight) type has an offset different from the
-		** most recently used offset,
-		** append an (unused) copy of the most recently used type
-		** (to help get global "altzone" and "timezone" variables
-		** set correctly).
-		*/
-		{
-			register int	mrudst, mrustd, hidst, histd, type;
-
-			hidst = histd = mrudst = mrustd = -1;
-			for (i = thistimei; i < thistimelim; ++i)
-				if (isdsts[types[i]])
-					mrudst = types[i];
-				else	mrustd = types[i];
-			for (i = 0; i < typecnt; ++i)
-				if (writetype[i]) {
-					if (isdsts[i])
-						hidst = i;
-					else	histd = i;
-				}
-			if (hidst >= 0 && mrudst >= 0 && hidst != mrudst &&
-				gmtoffs[hidst] != gmtoffs[mrudst]) {
-					isdsts[mrudst] = -1;
-					type = addtype(gmtoffs[mrudst],
-						&chars[abbrinds[mrudst]],
-						TRUE,
-						ttisstds[mrudst],
-						ttisgmts[mrudst]);
-					isdsts[mrudst] = TRUE;
-					writetype[type] = TRUE;
-			}
-			if (histd >= 0 && mrustd >= 0 && histd != mrustd &&
-				gmtoffs[histd] != gmtoffs[mrustd]) {
-					isdsts[mrustd] = -1;
-					type = addtype(gmtoffs[mrustd],
-						&chars[abbrinds[mrustd]],
-						FALSE,
-						ttisstds[mrustd],
-						ttisgmts[mrustd]);
-					isdsts[mrustd] = FALSE;
-					writetype[type] = TRUE;
-			}
-		}
-#endif /* !defined LEAVE_SOME_PRE_2011_SYSTEMS_IN_THE_LURCH */
-		thistypecnt = 0;
-		for (i = 0; i < typecnt; ++i)
-			typemap[i] = writetype[i] ?  thistypecnt++ : -1;
-		for (i = 0; i < sizeof indmap / sizeof indmap[0]; ++i)
-			indmap[i] = -1;
-		thischarcnt = 0;
-		for (i = 0; i < typecnt; ++i) {
-			register char *	thisabbr;
-
-			if (!writetype[i])
-				continue;
-			if (indmap[abbrinds[i]] >= 0)
-				continue;
-			thisabbr = &chars[abbrinds[i]];
-			for (j = 0; j < thischarcnt; ++j)
-				if (strcmp(&thischars[j], thisabbr) == 0)
-					break;
-			if (j == thischarcnt) {
-				(void) strcpy(&thischars[(int) thischarcnt],
-					thisabbr);
-				thischarcnt += strlen(thisabbr) + 1;
-			}
-			indmap[abbrinds[i]] = j;
-		}
-#define DO(field)	(void) fwrite((void *) tzh.field, \
-				(size_t) sizeof tzh.field, (size_t) 1, fp)
-		tzh = tzh0;
-		(void) strncpy(tzh.tzh_magic, TZ_MAGIC, sizeof tzh.tzh_magic);
-		tzh.tzh_version[0] = ZIC_VERSION;
-		convert(eitol(thistypecnt), tzh.tzh_ttisgmtcnt);
-		convert(eitol(thistypecnt), tzh.tzh_ttisstdcnt);
-		convert(eitol(thisleapcnt), tzh.tzh_leapcnt);
-		convert(eitol(thistimecnt), tzh.tzh_timecnt);
-		convert(eitol(thistypecnt), tzh.tzh_typecnt);
-		convert(eitol(thischarcnt), tzh.tzh_charcnt);
-		DO(tzh_magic);
-		DO(tzh_version);
-		DO(tzh_reserved);
-		DO(tzh_ttisgmtcnt);
-		DO(tzh_ttisstdcnt);
-		DO(tzh_leapcnt);
-		DO(tzh_timecnt);
-		DO(tzh_typecnt);
-		DO(tzh_charcnt);
-#undef DO
-		for (i = thistimei; i < thistimelim; ++i)
-			if (pass == 1)
-				puttzcode((long) ats[i], fp);
-			else	puttzcode64(ats[i], fp);
-		for (i = thistimei; i < thistimelim; ++i) {
-			unsigned char	uc;
-
-			uc = typemap[types[i]];
-			(void) fwrite((void *) &uc,
-				(size_t) sizeof uc,
-				(size_t) 1,
-				fp);
-		}
-		for (i = 0; i < typecnt; ++i)
-			if (writetype[i]) {
-				puttzcode(gmtoffs[i], fp);
-				(void) putc(isdsts[i], fp);
-				(void) putc((unsigned char) indmap[abbrinds[i]], fp);
-			}
-		if (thischarcnt != 0)
-			(void) fwrite((void *) thischars,
-				(size_t) sizeof thischars[0],
-				(size_t) thischarcnt, fp);
-		for (i = thisleapi; i < thisleaplim; ++i) {
-			register zic_t	todo;
-
-			if (roll[i]) {
-				if (timecnt == 0 || trans[i] < ats[0]) {
-					j = 0;
-					while (isdsts[j])
-						if (++j >= typecnt) {
-							j = 0;
-							break;
-						}
-				} else {
-					j = 1;
-					while (j < timecnt &&
-						trans[i] >= ats[j])
-							++j;
-					j = types[j - 1];
-				}
-				todo = tadd(trans[i], -gmtoffs[j]);
-			} else	todo = trans[i];
-			if (pass == 1)
-				puttzcode((long) todo, fp);
-			else	puttzcode64(todo, fp);
-			puttzcode(corr[i], fp);
-		}
-		for (i = 0; i < typecnt; ++i)
-			if (writetype[i])
-				(void) putc(ttisstds[i], fp);
-		for (i = 0; i < typecnt; ++i)
-			if (writetype[i])
-				(void) putc(ttisgmts[i], fp);
-	}
-	(void) fprintf(fp, "\n%s\n", string);
-	if (ferror(fp) || fclose(fp))
-		errx(EXIT_FAILURE, _("error writing %s"), fullname);
-	if (chmod(fullname, mflag) < 0)
-		err(EXIT_FAILURE, _("cannot change mode of %s to %03o"),
-		    fullname, (unsigned)mflag);
-	if ((uflag != (uid_t)-1 || gflag != (gid_t)-1)
-	    && chown(fullname, uflag, gflag) < 0)
-		err(EXIT_FAILURE, _("cannot change ownership of %s"), 
-		    fullname);
-}
-
-static void
-doabbr(abbr, format, letters, isdst, doquotes)
-char * const		abbr;
-const char * const	format;
-const char * const	letters;
-const int		isdst;
-const int		doquotes;
-{
-	register char *	cp;
-	register char *	slashp;
-	register int	len;
-
-	slashp = strchr(format, '/');
-	if (slashp == NULL) {
-		if (letters == NULL)
-			(void) strcpy(abbr, format);
-		else	(void) sprintf(abbr, format, letters);
-	} else if (isdst) {
-		(void) strcpy(abbr, slashp + 1);
-	} else {
-		if (slashp > format)
-			(void) strncpy(abbr, format,
-				(unsigned) (slashp - format));
-		abbr[slashp - format] = '\0';
-	}
-	if (!doquotes)
-		return;
-	for (cp = abbr; *cp != '\0'; ++cp)
-		if (strchr("ABCDEFGHIJKLMNOPQRSTUVWXYZ", *cp) == NULL &&
-			strchr("abcdefghijklmnopqrstuvwxyz", *cp) == NULL)
-				break;
-	len = strlen(abbr);
-	if (len > 0 && *cp == '\0')
-		return;
-	abbr[len + 2] = '\0';
-	abbr[len + 1] = '>';
-	for ( ; len > 0; --len)
-		abbr[len] = abbr[len - 1];
-	abbr[0] = '<';
-}
-
-static void
-updateminmax(x)
-const int	x;
-{
-	if (min_year > x)
-		min_year = x;
-	if (max_year < x)
-		max_year = x;
-}
-
-static int
-stringoffset(result, offset)
-char *	result;
-long	offset;
-{
-	register int	hours;
-	register int	minutes;
-	register int	seconds;
-
-	result[0] = '\0';
-	if (offset < 0) {
-		(void) strcpy(result, "-");
-		offset = -offset;
-	}
-	seconds = offset % SECSPERMIN;
-	offset /= SECSPERMIN;
-	minutes = offset % MINSPERHOUR;
-	offset /= MINSPERHOUR;
-	hours = offset;
-	if (hours >= HOURSPERDAY) {
-		result[0] = '\0';
-		return -1;
-	}
-	(void) sprintf(end(result), "%d", hours);
-	if (minutes != 0 || seconds != 0) {
-		(void) sprintf(end(result), ":%02d", minutes);
-		if (seconds != 0)
-			(void) sprintf(end(result), ":%02d", seconds);
-	}
-	return 0;
-}
-
-static int
-stringrule(result, rp, dstoff, gmtoff)
-char *				result;
-const struct rule * const	rp;
-const long			dstoff;
-const long			gmtoff;
-{
-	register long	tod;
-
-	result = end(result);
-	if (rp->r_dycode == DC_DOM) {
-		register int	month, total;
-
-		if (rp->r_dayofmonth == 29 && rp->r_month == TM_FEBRUARY)
-			return -1;
-		total = 0;
-		for (month = 0; month < rp->r_month; ++month)
-			total += len_months[0][month];
-		(void) sprintf(result, "J%d", total + rp->r_dayofmonth);
-	} else {
-		register int	week;
-
-		if (rp->r_dycode == DC_DOWGEQ) {
-			week = 1 + rp->r_dayofmonth / DAYSPERWEEK;
-			if ((week - 1) * DAYSPERWEEK + 1 != rp->r_dayofmonth)
-				return -1;
-		} else if (rp->r_dycode == DC_DOWLEQ) {
-			if (rp->r_dayofmonth == len_months[1][rp->r_month])
-				week = 5;
-			else {
-				week = 1 + rp->r_dayofmonth / DAYSPERWEEK;
-				if (week * DAYSPERWEEK - 1 != rp->r_dayofmonth)
-					return -1;
-			}
-		} else	return -1;	/* "cannot happen" */
-		(void) sprintf(result, "M%d.%d.%d",
-			rp->r_month + 1, week, rp->r_wday);
-	}
-	tod = rp->r_tod;
-	if (rp->r_todisgmt)
-		tod += gmtoff;
-	if (rp->r_todisstd && rp->r_stdoff == 0)
-		tod += dstoff;
-	if (tod < 0) {
-		result[0] = '\0';
-		return -1;
-	}
-	if (tod != 2 * SECSPERMIN * MINSPERHOUR) {
-		(void) strcat(result, "/");
-		if (stringoffset(end(result), tod) != 0)
-			return -1;
-	}
-	return 0;
-}
-
-static void
-stringzone(result, zpfirst, zonecount)
-char *				result;
-const struct zone * const	zpfirst;
-const int			zonecount;
-{
-	register const struct zone *	zp;
-	register struct rule *		rp;
-	register struct rule *		stdrp;
-	register struct rule *		dstrp;
-	register int			i;
-	register const char *		abbrvar;
-
-	result[0] = '\0';
-	zp = zpfirst + zonecount - 1;
-	stdrp = dstrp = NULL;
-	for (i = 0; i < zp->z_nrules; ++i) {
-		rp = &zp->z_rules[i];
-		if (rp->r_hiwasnum || rp->r_hiyear != INT_MAX)
-			continue;
-		if (rp->r_yrtype != NULL)
-			continue;
-		if (rp->r_stdoff == 0) {
-			if (stdrp == NULL)
-				stdrp = rp;
-			else	return;
-		} else {
-			if (dstrp == NULL)
-				dstrp = rp;
-			else	return;
-		}
-	}
-	if (stdrp == NULL && dstrp == NULL) {
-		/*
-		** There are no rules running through "max".
-		** Let's find the latest rule.
-		*/
-		for (i = 0; i < zp->z_nrules; ++i) {
-			rp = &zp->z_rules[i];
-			if (stdrp == NULL || rp->r_hiyear > stdrp->r_hiyear ||
-				(rp->r_hiyear == stdrp->r_hiyear &&
-				rp->r_month > stdrp->r_month))
-					stdrp = rp;
-		}
-		if (stdrp != NULL && stdrp->r_stdoff != 0)
-			return;	/* We end up in DST (a POSIX no-no). */
-		/*
-		** Horrid special case: if year is 2037,
-		** presume this is a zone handled on a year-by-year basis;
-		** do not try to apply a rule to the zone.
-		*/
-		if (stdrp != NULL && stdrp->r_hiyear == 2037)
-			return;
-	}
-	if (stdrp == NULL && (zp->z_nrules != 0 || zp->z_stdoff != 0))
-		return;
-	abbrvar = (stdrp == NULL) ? "" : stdrp->r_abbrvar;
-	doabbr(result, zp->z_format, abbrvar, FALSE, TRUE);
-	if (stringoffset(end(result), -zp->z_gmtoff) != 0) {
-		result[0] = '\0';
-		return;
-	}
-	if (dstrp == NULL)
-		return;
-	doabbr(end(result), zp->z_format, dstrp->r_abbrvar, TRUE, TRUE);
-	if (dstrp->r_stdoff != SECSPERMIN * MINSPERHOUR)
-		if (stringoffset(end(result),
-			-(zp->z_gmtoff + dstrp->r_stdoff)) != 0) {
-				result[0] = '\0';
-				return;
-		}
-	(void) strcat(result, ",");
-	if (stringrule(result, dstrp, dstrp->r_stdoff, zp->z_gmtoff) != 0) {
-		result[0] = '\0';
-		return;
-	}
-	(void) strcat(result, ",");
-	if (stringrule(result, stdrp, dstrp->r_stdoff, zp->z_gmtoff) != 0) {
-		result[0] = '\0';
-		return;
-	}
-}
-
-static void
-outzone(zpfirst, zonecount)
-const struct zone * const	zpfirst;
-const int			zonecount;
-{
-	register const struct zone *	zp;
-	register struct rule *		rp;
-	register int			i, j;
-	register int			usestart, useuntil;
-	register zic_t			starttime, untiltime;
-	register long			gmtoff;
-	register long			stdoff;
-	register int			year;
-	register long			startoff;
-	register int			startttisstd;
-	register int			startttisgmt;
-	register int			type;
-	register char *			startbuf;
-	register char *			ab;
-	register char *			envvar;
-	register int			max_abbr_len;
-	register int			max_envvar_len;
-
-	max_abbr_len = 2 + max_format_len + max_abbrvar_len;
-	max_envvar_len = 2 * max_abbr_len + 5 * 9;
-	startbuf = emalloc(max_abbr_len + 1);
-	ab = emalloc(max_abbr_len + 1);
-	envvar = emalloc(max_envvar_len + 1);
-	INITIALIZE(untiltime);
-	INITIALIZE(starttime);
-	/*
-	** Now. . .finally. . .generate some useful data!
-	*/
-	timecnt = 0;
-	typecnt = 0;
-	charcnt = 0;
-	/*
-	** Thanks to Earl Chew
-	** for noting the need to unconditionally initialize startttisstd.
-	*/
-	startttisstd = FALSE;
-	startttisgmt = FALSE;
-	min_year = max_year = EPOCH_YEAR;
-	if (leapseen) {
-		updateminmax(leapminyear);
-		updateminmax(leapmaxyear + (leapmaxyear < INT_MAX));
-	}
-	for (i = 0; i < zonecount; ++i) {
-		zp = &zpfirst[i];
-		if (i < zonecount - 1)
-			updateminmax(zp->z_untilrule.r_loyear);
-		for (j = 0; j < zp->z_nrules; ++j) {
-			rp = &zp->z_rules[j];
-			if (rp->r_lowasnum)
-				updateminmax(rp->r_loyear);
-			if (rp->r_hiwasnum)
-				updateminmax(rp->r_hiyear);
-		}
-	}
-	/*
-	** Generate lots of data if a rule can't cover all future times.
-	*/
-	stringzone(envvar, zpfirst, zonecount);
-	if (noise && envvar[0] == '\0') {
-		register char *	wp;
-
-wp = ecpyalloc(_("no POSIX environment variable for zone"));
-		wp = ecatalloc(wp, " ");
-		wp = ecatalloc(wp, zpfirst->z_name);
-		warning(wp);
-		ifree(wp);
-	}
-	if (envvar[0] == '\0') {
-		if (min_year >= INT_MIN + YEARSPERREPEAT)
-			min_year -= YEARSPERREPEAT;
-		else	min_year = INT_MIN;
-		if (max_year <= INT_MAX - YEARSPERREPEAT)
-			max_year += YEARSPERREPEAT;
-		else	max_year = INT_MAX;
-	}
-	/*
-	** For the benefit of older systems,
-	** generate data from 1900 through 2037.
-	*/
-	if (min_year > 1900)
-		min_year = 1900;
-	if (max_year < 2037)
-		max_year = 2037;
-	for (i = 0; i < zonecount; ++i) {
-		/*
-		** A guess that may well be corrected later.
-		*/
-		stdoff = 0;
-		zp = &zpfirst[i];
-		usestart = i > 0 && (zp - 1)->z_untiltime > min_time;
-		useuntil = i < (zonecount - 1);
-		if (useuntil && zp->z_untiltime <= min_time)
-			continue;
-		gmtoff = zp->z_gmtoff;
-		eat(zp->z_filename, zp->z_linenum);
-		*startbuf = '\0';
-		startoff = zp->z_gmtoff;
-		if (zp->z_nrules == 0) {
-			stdoff = zp->z_stdoff;
-			doabbr(startbuf, zp->z_format,
-				(char *) NULL, stdoff != 0, FALSE);
-			type = addtype(oadd(zp->z_gmtoff, stdoff),
-				startbuf, stdoff != 0, startttisstd,
-				startttisgmt);
-			if (usestart) {
-				addtt(starttime, type);
-				usestart = FALSE;
-			} else if (stdoff != 0)
-				addtt(min_time, type);
-		} else for (year = min_year; year <= max_year; ++year) {
-			if (useuntil && year > zp->z_untilrule.r_hiyear)
-				break;
-			/*
-			** Mark which rules to do in the current year.
-			** For those to do, calculate rpytime(rp, year);
-			*/
-			for (j = 0; j < zp->z_nrules; ++j) {
-				rp = &zp->z_rules[j];
-				eats(zp->z_filename, zp->z_linenum,
-					rp->r_filename, rp->r_linenum);
-				rp->r_todo = year >= rp->r_loyear &&
-						year <= rp->r_hiyear &&
-						yearistype(year, rp->r_yrtype);
-				if (rp->r_todo)
-					rp->r_temp = rpytime(rp, year);
-			}
-			for ( ; ; ) {
-				register int	k;
-				register zic_t	jtime, ktime;
-				register long	offset;
-
-				INITIALIZE(ktime);
-				if (useuntil) {
-					/*
-					** Turn untiltime into UTC
-					** assuming the current gmtoff and
-					** stdoff values.
-					*/
-					untiltime = zp->z_untiltime;
-					if (!zp->z_untilrule.r_todisgmt)
-						untiltime = tadd(untiltime,
-							-gmtoff);
-					if (!zp->z_untilrule.r_todisstd)
-						untiltime = tadd(untiltime,
-							-stdoff);
-				}
-				/*
-				** Find the rule (of those to do, if any)
-				** that takes effect earliest in the year.
-				*/
-				k = -1;
-				for (j = 0; j < zp->z_nrules; ++j) {
-					rp = &zp->z_rules[j];
-					if (!rp->r_todo)
-						continue;
-					eats(zp->z_filename, zp->z_linenum,
-						rp->r_filename, rp->r_linenum);
-					offset = rp->r_todisgmt ? 0 : gmtoff;
-					if (!rp->r_todisstd)
-						offset = oadd(offset, stdoff);
-					jtime = rp->r_temp;
-					if (jtime == min_time ||
-						jtime == max_time)
-							continue;
-					jtime = tadd(jtime, -offset);
-					if (k < 0 || jtime < ktime) {
-						k = j;
-						ktime = jtime;
-					}
-				}
-				if (k < 0)
-					break;	/* go on to next year */
-				rp = &zp->z_rules[k];
-				rp->r_todo = FALSE;
-				if (useuntil && ktime >= untiltime)
-					break;
-				stdoff = rp->r_stdoff;
-				if (usestart && ktime == starttime)
-					usestart = FALSE;
-				if (usestart) {
-					if (ktime < starttime) {
-						startoff = oadd(zp->z_gmtoff,
-							stdoff);
-						doabbr(startbuf, zp->z_format,
-							rp->r_abbrvar,
-							rp->r_stdoff != 0,
-							FALSE);
-						continue;
-					}
-					if (*startbuf == '\0' &&
-						startoff == oadd(zp->z_gmtoff,
-						stdoff)) {
-							doabbr(startbuf,
-								zp->z_format,
-								rp->r_abbrvar,
-								rp->r_stdoff !=
-								0,
-								FALSE);
-					}
-				}
-				eats(zp->z_filename, zp->z_linenum,
-					rp->r_filename, rp->r_linenum);
-				doabbr(ab, zp->z_format, rp->r_abbrvar,
-					rp->r_stdoff != 0, FALSE);
-				offset = oadd(zp->z_gmtoff, rp->r_stdoff);
-				type = addtype(offset, ab, rp->r_stdoff != 0,
-					rp->r_todisstd, rp->r_todisgmt);
-				addtt(ktime, type);
-			}
-		}
-		if (usestart) {
-			if (*startbuf == '\0' &&
-				zp->z_format != NULL &&
-				strchr(zp->z_format, '%') == NULL &&
-				strchr(zp->z_format, '/') == NULL)
-					(void) strcpy(startbuf, zp->z_format);
-			eat(zp->z_filename, zp->z_linenum);
-			if (*startbuf == '\0')
-error(_("can't determine time zone abbreviation to use just after until time"));
-			else	addtt(starttime,
-					addtype(startoff, startbuf,
-						startoff != zp->z_gmtoff,
-						startttisstd,
-						startttisgmt));
-		}
-		/*
-		** Now we may get to set starttime for the next zone line.
-		*/
-		if (useuntil) {
-			startttisstd = zp->z_untilrule.r_todisstd;
-			startttisgmt = zp->z_untilrule.r_todisgmt;
-			starttime = zp->z_untiltime;
-			if (!startttisstd)
-				starttime = tadd(starttime, -stdoff);
-			if (!startttisgmt)
-				starttime = tadd(starttime, -gmtoff);
-		}
-	}
-	writezone(zpfirst->z_name, envvar);
-	ifree(startbuf);
-	ifree(ab);
-	ifree(envvar);
-}
-
-static void
-addtt(starttime, type)
-const zic_t	starttime;
-int		type;
-{
-	if (starttime <= min_time ||
-		(timecnt == 1 && attypes[0].at < min_time)) {
-		gmtoffs[0] = gmtoffs[type];
-		isdsts[0] = isdsts[type];
-		ttisstds[0] = ttisstds[type];
-		ttisgmts[0] = ttisgmts[type];
-		if (abbrinds[type] != 0)
-			(void) strcpy(chars, &chars[abbrinds[type]]);
-		abbrinds[0] = 0;
-		charcnt = strlen(chars) + 1;
-		typecnt = 1;
-		timecnt = 0;
-		type = 0;
-	}
-	if (timecnt >= TZ_MAX_TIMES) {
-		error(_("too many transitions?!"));
-		exit(EXIT_FAILURE);
-	}
-	attypes[timecnt].at = starttime;
-	attypes[timecnt].type = type;
-	++timecnt;
-}
-
-static int
-addtype(gmtoff, abbr, isdst, ttisstd, ttisgmt)
-const long		gmtoff;
-const char * const	abbr;
-const int		isdst;
-const int		ttisstd;
-const int		ttisgmt;
-{
-	register int	i, j;
-
-	if (isdst != TRUE && isdst != FALSE) {
-		error(_("internal error - addtype called with bad isdst"));
-		exit(EXIT_FAILURE);
-	}
-	if (ttisstd != TRUE && ttisstd != FALSE) {
-		error(_("internal error - addtype called with bad ttisstd"));
-		exit(EXIT_FAILURE);
-	}
-	if (ttisgmt != TRUE && ttisgmt != FALSE) {
-		error(_("internal error - addtype called with bad ttisgmt"));
-		exit(EXIT_FAILURE);
-	}
-	/*
-	** See if there's already an entry for this zone type.
-	** If so, just return its index.
-	*/
-	for (i = 0; i < typecnt; ++i) {
-		if (gmtoff == gmtoffs[i] && isdst == isdsts[i] &&
-			strcmp(abbr, &chars[abbrinds[i]]) == 0 &&
-			ttisstd == ttisstds[i] &&
-			ttisgmt == ttisgmts[i])
-				return i;
-	}
-	/*
-	** There isn't one; add a new one, unless there are already too
-	** many.
-	*/
-	if (typecnt >= TZ_MAX_TYPES) {
-		error(_("too many local time types"));
-		exit(EXIT_FAILURE);
-	}
-	if (! (-1L - 2147483647L <= gmtoff && gmtoff <= 2147483647L)) {
-		error(_("UTC offset out of range"));
-		exit(EXIT_FAILURE);
-	}
-	gmtoffs[i] = gmtoff;
-	isdsts[i] = isdst;
-	ttisstds[i] = ttisstd;
-	ttisgmts[i] = ttisgmt;
-
-	for (j = 0; j < charcnt; ++j)
-		if (strcmp(&chars[j], abbr) == 0)
-			break;
-	if (j == charcnt)
-		newabbr(abbr);
-	abbrinds[i] = j;
-	++typecnt;
-	return i;
-}
-
-static void
-leapadd(t, positive, rolling, count)
-const zic_t	t;
-const int	positive;
-const int	rolling;
-int		count;
-{
-	register int	i, j;
-
-	if (leapcnt + (positive ? count : 1) > TZ_MAX_LEAPS) {
-		error(_("too many leap seconds"));
-		exit(EXIT_FAILURE);
-	}
-	for (i = 0; i < leapcnt; ++i)
-		if (t <= trans[i]) {
-			if (t == trans[i]) {
-				error(_("repeated leap second moment"));
-				exit(EXIT_FAILURE);
-			}
-			break;
-		}
-	do {
-		for (j = leapcnt; j > i; --j) {
-			trans[j] = trans[j - 1];
-			corr[j] = corr[j - 1];
-			roll[j] = roll[j - 1];
-		}
-		trans[i] = t;
-		corr[i] = positive ? 1L : eitol(-count);
-		roll[i] = rolling;
-		++leapcnt;
-	} while (positive && --count != 0);
-}
-
-static void
-adjleap(void)
-{
-	register int	i;
-	register long	last = 0;
-
-	/*
-	** propagate leap seconds forward
-	*/
-	for (i = 0; i < leapcnt; ++i) {
-		trans[i] = tadd(trans[i], last);
-		last = corr[i] += last;
-	}
-}
-
-static int
-yearistype(year, type)
-const int		year;
-const char * const	type;
-{
-	static char *	buf;
-	int		result;
-
-	if (type == NULL || *type == '\0')
-		return TRUE;
-	buf = erealloc(buf, (int) (132 + strlen(yitcommand) + strlen(type)));
-	(void) sprintf(buf, "%s %d %s", yitcommand, year, type);
-	result = system(buf);
-	if (WIFEXITED(result)) switch (WEXITSTATUS(result)) {
-		case 0:
-			return TRUE;
-		case 1:
-			return FALSE;
-	}
-	error(_("wild result from command execution"));
-	warnx(_("command was '%s', result was %d"), buf, result);
-	for ( ; ; )
-		exit(EXIT_FAILURE);
-}
-
-static int
-lowerit(a)
-int	a;
-{
-	a = (unsigned char) a;
-	return (isascii(a) && isupper(a)) ? tolower(a) : a;
-}
-
-static int
-ciequal(ap, bp)		/* case-insensitive equality */
-register const char *	ap;
-register const char *	bp;
-{
-	while (lowerit(*ap) == lowerit(*bp++))
-		if (*ap++ == '\0')
-			return TRUE;
-	return FALSE;
-}
-
-static int
-itsabbr(abbr, word)
-register const char *	abbr;
-register const char *	word;
-{
-	if (lowerit(*abbr) != lowerit(*word))
-		return FALSE;
-	++word;
-	while (*++abbr != '\0')
-		do {
-			if (*word == '\0')
-				return FALSE;
-		} while (lowerit(*word++) != lowerit(*abbr));
-	return TRUE;
-}
-
-static const struct lookup *
-byword(word, table)
-register const char * const		word;
-register const struct lookup * const	table;
-{
-	register const struct lookup *	foundlp;
-	register const struct lookup *	lp;
-
-	if (word == NULL || table == NULL)
-		return NULL;
-	/*
-	** Look for exact match.
-	*/
-	for (lp = table; lp->l_word != NULL; ++lp)
-		if (ciequal(word, lp->l_word))
-			return lp;
-	/*
-	** Look for inexact match.
-	*/
-	foundlp = NULL;
-	for (lp = table; lp->l_word != NULL; ++lp)
-		if (itsabbr(word, lp->l_word)) {
-			if (foundlp == NULL)
-				foundlp = lp;
-			else	return NULL;	/* multiple inexact matches */
-		}
-	return foundlp;
-}
-
-static char **
-getfields(cp)
-register char *	cp;
-{
-	register char *		dp;
-	register char **	array;
-	register int		nsubs;
-
-	if (cp == NULL)
-		return NULL;
-	array = (char **) (void *)
-		emalloc((int) ((strlen(cp) + 1) * sizeof *array));
-	nsubs = 0;
-	for ( ; ; ) {
-		while (isascii((unsigned char) *cp) &&
-			isspace((unsigned char) *cp))
-				++cp;
-		if (*cp == '\0' || *cp == '#')
-			break;
-		array[nsubs++] = dp = cp;
-		do {
-			if ((*dp = *cp++) != '"')
-				++dp;
-			else while ((*dp = *cp++) != '"')
-				if (*dp != '\0')
-					++dp;
-				else {
-					error(_("odd number of quotation marks"));
-					exit(EXIT_FAILURE);
-				}
-		} while (*cp != '\0' && *cp != '#' &&
-			(!isascii(*cp) || !isspace((unsigned char) *cp)));
-		if (isascii(*cp) && isspace((unsigned char) *cp))
-			++cp;
-		*dp = '\0';
-	}
-	array[nsubs] = NULL;
-	return array;
-}
-
-static long
-oadd(t1, t2)
-const long	t1;
-const long	t2;
-{
-	register long	t;
-
-	t = t1 + t2;
-	if ((t2 > 0 && t <= t1) || (t2 < 0 && t >= t1)) {
-		error(_("time overflow"));
-		exit(EXIT_FAILURE);
-	}
-	return t;
-}
-
-static zic_t
-tadd(t1, t2)
-const zic_t	t1;
-const long	t2;
-{
-	register zic_t	t;
-
-	if (t1 == max_time && t2 > 0)
-		return max_time;
-	if (t1 == min_time && t2 < 0)
-		return min_time;
-	t = t1 + t2;
-	if ((t2 > 0 && t <= t1) || (t2 < 0 && t >= t1)) {
-		error(_("time overflow"));
-		exit(EXIT_FAILURE);
-	}
-	return t;
-}
-
-/*
-** Given a rule, and a year, compute the date - in seconds since January 1,
-** 1970, 00:00 LOCAL time - in that year that the rule refers to.
-*/
-
-static zic_t
-rpytime(rp, wantedy)
-register const struct rule * const	rp;
-register const int			wantedy;
-{
-	register int	y, m, i;
-	register long	dayoff;			/* with a nod to Margaret O. */
-	register zic_t	t;
-
-	if (wantedy == INT_MIN)
-		return min_time;
-	if (wantedy == INT_MAX)
-		return max_time;
-	dayoff = 0;
-	m = TM_JANUARY;
-	y = EPOCH_YEAR;
-	while (wantedy != y) {
-		if (wantedy > y) {
-			i = len_years[isleap(y)];
-			++y;
-		} else {
-			--y;
-			i = -len_years[isleap(y)];
-		}
-		dayoff = oadd(dayoff, eitol(i));
-	}
-	while (m != rp->r_month) {
-		i = len_months[isleap(y)][m];
-		dayoff = oadd(dayoff, eitol(i));
-		++m;
-	}
-	i = rp->r_dayofmonth;
-	if (m == TM_FEBRUARY && i == 29 && !isleap(y)) {
-		if (rp->r_dycode == DC_DOWLEQ)
-			--i;
-		else {
-			error(_("use of 2/29 in non leap-year"));
-			exit(EXIT_FAILURE);
-		}
-	}
-	--i;
-	dayoff = oadd(dayoff, eitol(i));
-	if (rp->r_dycode == DC_DOWGEQ || rp->r_dycode == DC_DOWLEQ) {
-		register long	wday;
-
-#define LDAYSPERWEEK	((long) DAYSPERWEEK)
-		wday = eitol(EPOCH_WDAY);
-		/*
-		** Don't trust mod of negative numbers.
-		*/
-		if (dayoff >= 0)
-			wday = (wday + dayoff) % LDAYSPERWEEK;
-		else {
-			wday -= ((-dayoff) % LDAYSPERWEEK);
-			if (wday < 0)
-				wday += LDAYSPERWEEK;
-		}
-		while (wday != eitol(rp->r_wday))
-			if (rp->r_dycode == DC_DOWGEQ) {
-				dayoff = oadd(dayoff, (long) 1);
-				if (++wday >= LDAYSPERWEEK)
-					wday = 0;
-				++i;
-			} else {
-				dayoff = oadd(dayoff, (long) -1);
-				if (--wday < 0)
-					wday = LDAYSPERWEEK - 1;
-				--i;
-			}
-		if (i < 0 || i >= len_months[isleap(y)][m]) {
-			if (noise)
-				warning(_("rule goes past start/end of month--\
-will not work with pre-2004 versions of zic"));
-		}
-	}
-	if (dayoff < min_time / SECSPERDAY)
-		return min_time;
-	if (dayoff > max_time / SECSPERDAY)
-		return max_time;
-	t = (zic_t) dayoff * SECSPERDAY;
-	return tadd(t, rp->r_tod);
-}
-
-static void
-newabbr(string)
-const char * const	string;
-{
-	register int	i;
-
-	if (strcmp(string, GRANDPARENTED) != 0) {
-		register const char *	cp;
-		register char *		wp;
-
-		cp = string;
-		wp = NULL;
-		while (isascii((unsigned char) *cp) &&
-			(isalnum((unsigned char)*cp) || *cp == '-' || *cp == '+'))
-				++cp;
-		if (noise && cp - string > 3)
-wp = _("time zone abbreviation has more than 3 characters");
-		if (cp - string > ZIC_MAX_ABBR_LEN_WO_WARN)
-wp = _("time zone abbreviation has too many characters");
-		if (*cp != '\0')
-wp = _("time zone abbreviation differs from POSIX standard");
-		if (wp != NULL) {
-			wp = ecpyalloc(wp);
-			wp = ecatalloc(wp, " (");
-			wp = ecatalloc(wp, string);
-			wp = ecatalloc(wp, ")");
-			warning(wp);
-			ifree(wp);
-		}
-	}
-	i = strlen(string) + 1;
-	if (charcnt + i > TZ_MAX_CHARS) {
-		error(_("too many, or too long, time zone abbreviations"));
-		exit(EXIT_FAILURE);
-	}
-	(void) strcpy(&chars[charcnt], string);
-	charcnt += eitol(i);
-}
-
-static int
-mkdirs(argname)
-char *		argname;
-{
-	register char *	name;
-	register char *	cp;
-
-	if (argname == NULL || *argname == '\0' || Dflag)
-		return 0;
-	cp = name = ecpyalloc(argname);
-	while ((cp = strchr(cp + 1, '/')) != 0) {
-		*cp = '\0';
-#ifndef unix
-		/*
-		** DOS drive specifier?
-		*/
-		if (isalpha((unsigned char) name[0]) &&
-			name[1] == ':' && name[2] == '\0') {
-				*cp = '/';
-				continue;
-		}
-#endif /* !defined unix */
-		if (!itsdir(name)) {
-			/*
-			** It doesn't seem to exist, so we try to create it.
-			** Creation may fail because of the directory being
-			** created by some other multiprocessor, so we get
-			** to do extra checking.
-			*/
-			if (mkdir(name, MKDIR_UMASK) != 0
-				&& (errno != EEXIST || !itsdir(name))) {
-				warn(_("can't create directory %s"), name);
-				ifree(name);
-				return -1;
-			}
-		}
-		*cp = '/';
-	}
-	ifree(name);
-	return 0;
-}
-
-static long
-eitol(i)
-const int	i;
-{
-	long	l;
-
-	l = i;
-	if ((i < 0 && l >= 0) || (i == 0 && l != 0) || (i > 0 && l <= 0))
-		errx(EXIT_FAILURE, _("%d did not sign extend correctly"), i);
-	return l;
-}
-
-#include <grp.h>
-#include <pwd.h>
-
-static void
-setgroup(flag, name)
-	gid_t *flag;
-	const char *name;
-{
-	struct group *gr;
-
-	if (*flag != (gid_t)-1)
-		errx(EXIT_FAILURE, _("multiple -g flags specified"));
-
-	gr = getgrnam(name);
-	if (gr == 0) {
-		char *ep;
-		unsigned long ul;
-
-		ul = strtoul(name, &ep, 10);
-		if (ul == (unsigned long)(gid_t)ul && *ep == '\0') {
-			*flag = ul;
-			return;
-		}
-		errx(EXIT_FAILURE, _("group `%s' not found"), name);
-	}
-	*flag = gr->gr_gid;
-}
-
-static void
-setuser(flag, name)
-	uid_t *flag;
-	const char *name;
-{
-	struct passwd *pw;
-
-	if (*flag != (gid_t)-1)
-		errx(EXIT_FAILURE, _("multiple -u flags specified"));
-
-	pw = getpwnam(name);
-	if (pw == 0) {
-		char *ep;
-		unsigned long ul;
-
-		ul = strtoul(name, &ep, 10);
-		if (ul == (unsigned long)(gid_t)ul && *ep == '\0') {
-			*flag = ul;
-			return;
-		}
-		errx(EXIT_FAILURE, _("user `%s' not found"), name);
-	}
-	*flag = pw->pw_uid;
-}
-
-/*
-** UNIX was a registered trademark of The Open Group in 2003.
-*/
diff --git a/contrib/tzcode/zic/zic/Makefile b/contrib/tzcode/zic/zic/Makefile
deleted file mode 100644
index 02dc6e2d710e..000000000000
--- a/contrib/tzcode/zic/zic/Makefile
+++ /dev/null
@@ -1,16 +0,0 @@
-# $FreeBSD$
-
-.PATH: ${.CURDIR}/..
-
-PROG=	zic
-MAN=	zic.8
-SRCS=	zic.c ialloc.c scheck.c
-
-CFLAGS+= -DTM_GMTOFF=tm_gmtoff -DTM_ZONE=tm_zone -DSTD_INSPIRED -DPCTS
-CFLAGS+= -DHAVE_LONG_DOUBLE -DTZDIR=\"/usr/share/zoneinfo\" -Demkdir=mkdir
-CFLAGS+= -DHAVE_STRERROR -DHAVE_UNISTD_H
-CFLAGS+= -I${.CURDIR}/.. -I${.CURDIR}/../../../lib/libc/stdtime
-
-WARNS?=	2
-
-.include <bsd.prog.mk>
diff --git a/lib/libc/stdtime/Makefile.inc b/lib/libc/stdtime/Makefile.inc
index 3d483469bc97..a7ef64650ba1 100644
--- a/lib/libc/stdtime/Makefile.inc
+++ b/lib/libc/stdtime/Makefile.inc
@@ -1,19 +1,21 @@
 #	Makefile.inc,v 1.2 1994/09/13 21:26:01 wollman Exp
 # $FreeBSD$
 
-.PATH:	${LIBC_SRCTOP}/stdtime ${SRCTOP}/contrib/tzcode/stdtime
+.PATH:	${LIBC_SRCTOP}/stdtime ${SRCTOP}/contrib/tzcode
 
 SRCS+=	asctime.c difftime.c localtime.c strftime.c strptime.c timelocal.c \
 	time32.c
 
 SYM_MAPS+= ${LIBC_SRCTOP}/stdtime/Symbol.map
 
-CFLAGS+= -I${SRCTOP}/contrib/tzcode/stdtime -I${LIBC_SRCTOP}/stdtime
+CFLAGS+= -I${SRCTOP}/contrib/tzcode -I${LIBC_SRCTOP}/stdtime
 
 CFLAGS.localtime.c= -fwrapv
-
+CFLAGS.localtime.c+= -DALL_STATE -DTHREAD_SAFE
+CFLAGS.localtime.c+= -DHAVE_TZNAME=2 -DUSG_COMPAT=0 -DALTZONE=0
+CFLAGS.localtime.c+= -DNETBSD_INSPIRED=0 -DSTD_INSPIRED=1
 .if ${MK_DETECT_TZ_CHANGES} != "no"
-CFLAGS+= -DDETECT_TZ_CHANGES
+CFLAGS.localtime.c+= -DDETECT_TZ_CHANGES
 .endif
 
 MAN+=	ctime.3 strftime.3 strptime.3 time2posix.3
diff --git a/contrib/tzcode/stdtime/ctime.3 b/lib/libc/stdtime/ctime.3
index de3a57bab59e..de3a57bab59e 100644
--- a/contrib/tzcode/stdtime/ctime.3
+++ b/lib/libc/stdtime/ctime.3
diff --git a/lib/libc/stdtime/strftime.c b/lib/libc/stdtime/strftime.c
index 50fbc41de24e..722f2a36992b 100644
--- a/lib/libc/stdtime/strftime.c
+++ b/lib/libc/stdtime/strftime.c
@@ -42,6 +42,7 @@ __FBSDID("$FreeBSD$");
 #include "tzfile.h"
 #include <fcntl.h>
 #include <sys/stat.h>
+#include <stdio.h>
 #include "un-namespace.h"
 #include "timelocal.h"
 
diff --git a/lib/libc/stdtime/strptime.c b/lib/libc/stdtime/strptime.c
index 5691f61b6d84..d8d8962dcaee 100644
--- a/lib/libc/stdtime/strptime.c
+++ b/lib/libc/stdtime/strptime.c
@@ -54,6 +54,7 @@ __FBSDID("$FreeBSD$");
 #include <stdlib.h>
 #include <string.h>
 #include <pthread.h>
+#include "private.h"
 #include "un-namespace.h"
 #include "libc_private.h"
 #include "timelocal.h"
diff --git a/usr.sbin/Makefile b/usr.sbin/Makefile
index 5568691776b8..603733db9664 100644
--- a/usr.sbin/Makefile
+++ b/usr.sbin/Makefile
@@ -101,6 +101,7 @@ SUBDIR=	adduser \
 	wake \
 	watch \
 	watchdogd \
+	zdump \
 	zic \
 	zonectl
 
diff --git a/usr.sbin/zdump/Makefile b/usr.sbin/zdump/Makefile
new file mode 100644
index 000000000000..43e4edaae2b6
--- /dev/null
+++ b/usr.sbin/zdump/Makefile
@@ -0,0 +1,12 @@
+# $FreeBSD$
+
+.PATH: ${SRCTOP}/contrib/tzcode
+
+PROG=	zdump
+MAN=	zdump.8
+SRCS=	zdump.c
+
+CFLAGS+= -DNETBSD_INSPIRED=0 -DSTD_INSPIRED=1
+CFLAGS+= -I${SRCTOP}/contrib/tzcode
+
+.include <bsd.prog.mk>
diff --git a/usr.sbin/zic/zdump/Makefile.depend b/usr.sbin/zdump/Makefile.depend
index 6cfaab1c3644..6cfaab1c3644 100644
--- a/usr.sbin/zic/zdump/Makefile.depend
+++ b/usr.sbin/zdump/Makefile.depend
diff --git a/usr.sbin/zic/Makefile b/usr.sbin/zic/Makefile
index 9d699a891449..a3eb6f7dadba 100644
--- a/usr.sbin/zic/Makefile
+++ b/usr.sbin/zic/Makefile
@@ -1,7 +1,12 @@
 # $FreeBSD$
 
-# Vendor contact: tz@elsie.nci.nih.gov
+.PATH: ${SRCTOP}/contrib/tzcode
 
-SUBDIR=	zic zdump
+PROG=	zic
+MAN=	zic.8
+SRCS=	zic.c
 
-.include <bsd.subdir.mk>
+CFLAGS+= -DNETBSD_INSPIRED=0 -DSTD_INSPIRED=1
+CFLAGS+= -I${SRCTOP}/contrib/tzcode
+
+.include <bsd.prog.mk>
diff --git a/usr.sbin/zic/zic/Makefile.depend b/usr.sbin/zic/Makefile.depend
index 6cfaab1c3644..6cfaab1c3644 100644
--- a/usr.sbin/zic/zic/Makefile.depend
+++ b/usr.sbin/zic/Makefile.depend
diff --git a/usr.sbin/zic/Makefile.inc b/usr.sbin/zic/Makefile.inc
deleted file mode 100644
index 19a7ea422c5b..000000000000
--- a/usr.sbin/zic/Makefile.inc
+++ /dev/null
@@ -1,3 +0,0 @@
-# $FreeBSD$
-
-.include "${SRCTOP}/usr.sbin/Makefile.inc"
diff --git a/usr.sbin/zic/README b/usr.sbin/zic/README
deleted file mode 100644
index 5cb701eca276..000000000000
--- a/usr.sbin/zic/README
+++ /dev/null
@@ -1,88 +0,0 @@
-@(#)README	8.3
-This file is in the public domain, so clarified as of
-2009-05-17 by Arthur David Olson.
-
-$FreeBSD$
-
-"What time is it?" -- Richard Deacon as The King
-"Any time you want it to be." -- Frank Baxter as The Scientist
-					(from the Bell System film "About Time")
-
-The 1989 update of the time zone package featured
-
-*	POSIXization (including interpretation of POSIX-style TZ environment
-	variables, provided by Guy Harris),
-*	ANSIfication (including versions of "mktime" and "difftime"),
-*	SVIDulation (an "altzone" variable)
-*	MACHination (the "gtime" function)
-*	corrections to some time zone data (including corrections to the rules
-	for Great Britain and New Zealand)
-*	reference data from the United States Naval Observatory for folks who
-	want to do additional time zones
-*	and the 1989 data for Saudi Arabia.
-
-(Since this code will be treated as "part of the implementation" in some places
-and as "part of the application" in others, there's no good way to name
-functions, such as timegm, that are not part of the proposed ANSI C standard;
-such functions have kept their old, underscore-free names in this update.)
-
-And the "dysize" function has disappeared; it was present to allow compilation
-of the "date" command on old BSD systems, and a version of "date" is now
-provided in the package.  The "date" command is not created when you "make all"
-since it may lack options provided by the version distributed with your
-operating system, or may not interact with the system in the same way the
-native version does.
-
-Since POSIX frowns on correct leap second handling, the default behavior of
-the "zic" command (in the absence of a "-L" option) has been changed to omit
-leap second information from its output files.
-
-Here is a recipe for acquiring, building, installing, and testing the
-tz distribution on a GNU/Linux or similar host.
-
-	mkdir tz
-	cd tz
-	wget 'ftp://elsie.nci.nih.gov/pub/tz*.tar.gz'
-	gzip -dc tzcode*.tar.gz | tar -xf -
-	gzip -dc tzdata*.tar.gz | tar -xf -
-
-Be sure to read the comments in "Makefile" and make any changes needed
-to make things right for your system, especially if you are using some
-platform other than GNU/Linux.  Then run the following commands,
-substituting your desired installation directory for "$HOME/tzdir":
-
-	make TOPDIR=$HOME/tzdir install
-	$HOME/tzdir/etc/zdump -v America/Los_Angeles
-
-To use the new functions, use a "-ltz" option when compiling or linking.
-
-Historical local time information has been included here to:
-
-*	provide a compendium of data about the history of civil time
-	that is useful even if the data are not 100% accurate;
-
-*	give an idea of the variety of local time rules that have
-	existed in the past and thus an idea of the variety that may be
-	expected in the future;
-
-*	provide a test of the generality of the local time rule description
-	system.
-
-The information in the time zone data files is by no means authoritative;
-the files currently do not even attempt to cover all time stamps before
-1970, and there are undoubtedly errors even for time stamps since 1970.
-If you know that the rules are different from those in a file, by all means
-feel free to change file (and please send the changed version to
-tz@elsie.nci.nih.gov for use in the future).  Europeans take note!
-
-Thanks to these Timezone Caballeros who've made major contributions to the
-time conversion package:  Keith Bostic; Bob Devine; Paul Eggert; Robert Elz;
-Guy Harris; Mark Horton; John Mackin; and Bradley White.  Thanks also to
-Michael Bloom, Art Neilson, Stephen Prince, John Sovereign, and Frank Wales
-for testing work, and to Gwillim Law for checking local mean time data.
-None of them are responsible for remaining errors.
-
-Look in the ~ftp/pub directory of elsie.nci.nih.gov
-for updated versions of these files.
-
-Please send comments or information to tz@elsie.nci.nih.gov.
diff --git a/usr.sbin/zic/zdump/Makefile b/usr.sbin/zic/zdump/Makefile
deleted file mode 100644
index 9671e7bf5298..000000000000
--- a/usr.sbin/zic/zdump/Makefile
+++ /dev/null
@@ -1,15 +0,0 @@
-# $FreeBSD$
-
-.PATH: ${SRCTOP}/contrib/tzcode/zic
-
-PROG=	zdump
-MAN=	zdump.8
-SRCS=	zdump.c ialloc.c scheck.c
-
-CFLAGS+= -DTM_GMTOFF=tm_gmtoff -DTM_ZONE=tm_zone -DSTD_INSPIRED -DPCTS
-CFLAGS+= -DHAVE_LONG_DOUBLE -DTZDIR=\"${SHAREDIR}/zoneinfo\" -Demkdir=mkdir
-CFLAGS+= -I${.CURDIR:H} -I${SRCTOP}/contrib/tzcode/stdtime
-
-WARNS?=	2
-
-.include <bsd.prog.mk>
diff --git a/usr.sbin/zic/zic/Makefile b/usr.sbin/zic/zic/Makefile
deleted file mode 100644
index 17ffb33a57e7..000000000000
--- a/usr.sbin/zic/zic/Makefile
+++ /dev/null
@@ -1,22 +0,0 @@
-# $FreeBSD$
-
-.include <src.opts.mk>
-
-.PATH: ${SRCTOP}/contrib/tzcode/zic
-
-PROG=	zic
-MAN=	zic.8
-SRCS=	zic.c ialloc.c scheck.c
-
-CFLAGS+= -DTM_GMTOFF=tm_gmtoff -DTM_ZONE=tm_zone -DSTD_INSPIRED -DPCTS
-CFLAGS+= -DHAVE_LONG_DOUBLE -DTZDIR=\"${SHAREDIR}/zoneinfo\" -Demkdir=mkdir
-CFLAGS+= -DHAVE_STRERROR -DHAVE_UNISTD_H
-CFLAGS+= -I${.CURDIR:H} -I${SRCTOP}/contrib/tzcode/stdtime
-
-WARNS?=	2
-
-.if ${COMPILER_TYPE} == "gcc"
-CWARNFLAGS+=	-Wno-error=strict-overflow
-.endif
-
-.include <bsd.prog.mk>