Better copyright advice

Document the common practices around copyrights with "all rights reserved" in
them as new copyright notices get added.

It's an open question qhether to point people at the fact that since the Berne
convention was ratified, All rights reserved is largely obsolete.
https://en.wikipedia.org/wiki/All_rights_reserved#Obsolescence has the
details. The committer's guide will be revised shortly, and it's likely that's a
better place for this discussion. If not, I'll add a blurb here.

Reviewed by: jhb@, brooks@
Differential Review: https://reviews.freebsd.org/D22800

1 files changed, 28 insertions, 5 deletions

diff --git a/share/man/man9/style.9 b/share/man/man9/style.9
index 1a6f7d5e0cce..5e455d53c309 100644
--- a/share/man/man9/style.9
+++ b/share/man/man9/style.9
@@ -1,6 +1,5 @@
 .\"-
-.\" Copyright (c) 1995-2005 The FreeBSD Project
-.\" All rights reserved.
+.\" Copyright (c) 1995-2019 The FreeBSD Project
 .\"
 .\" Redistribution and use in source and binary forms, with or without
 .\" modification, are permitted provided that the following conditions
@@ -26,7 +25,7 @@
 .\"	From: @(#)style	1.14 (Berkeley) 4/28/95
 .\" $FreeBSD$
 .\"
-.Dd June 3, 2019
+.Dd December 13, 2019
 .Dt STYLE 9
 .Os
 .Sh NAME
@@ -84,8 +83,32 @@ comments.
 Comments starting in columns other than the first are never
 considered license statements.
 Use the appropriate SPDX-License-Identifier line before the copyright.
-.Pp
-After any copyright header, there is a blank line, and the
+If the copyright assertion contains the phrase
+.Dq Li "All Rights Reserved"
+that should be on the same line as the word
+.Dq Li "Copyright" .
+You should not insert a new copyright line between an old
+copyright line and this phrase.
+Instead, you should insert a new copyright phrase after
+a pre-existing
+.Dq Li "All Rights Reserved"
+line.
+When making changes, it is acceptable to fold an
+.Dq Li "All Rights Reserved"
+line with each of the
+.Dq Li "Copyright"
+lines.
+For files that have the
+.Dq Li "All Rights Reserved"
+line on the same line(s) as the word
+.Dq Li "Copyright" ,
+new copyright assertions should be added last.
+New
+.Dq Li "Copyright"
+lines should only be added when making substantial changes to the file,
+not for trivial changes.
+.Pp
+After any copyright and license comment, there is a blank line, and the
 .Li $\&FreeBSD$
 for non C/C++ language source files.
 Version control system ID tags should only exist once in a file