A common documentation file format that includes a list of changes between published (and sometimes unpublished) versions of software.
Debian packages have excellent changelogs. Here is an example of one, for the package of PerrysFirewallingScript that
CraigBox maintains:
linuxserver-firewall (0.65) unstable; urgency=low
* Add man page (thanks to John McPherson)
* Update README.Debian to refer to documentation
-- Craig Box <packages@wiki.example.org> Thu, 19 May 2005 10:45:33 +1200
linuxserver-firewall (0.64) unstable; urgency=low
* Remove ()s from sourcing rules.
-- Craig Box <packages@wiki.example.org> Mon, 9 May 2005 13:37:13 +1200
linuxserver-firewall (0.63) unstable; urgency=low
* Set LANG=C in firewall.functions in order to work around
bash accepting lower case letters in [A-Z].
Backed out some changes made to fix this.
-- Craig Box <packages@wiki.example.org> Thu, 5 May 2005 14:00:10 +1200
linuxserver-firewall (0.62) unstable; urgency=low
* Package for Ubuntu.
-- Craig Box <packages@wiki.example.org> Thu, 5 May 2005 10:46:41 +1200
linuxserver-firewall (0.61) unstable; urgency=low
* Fixed $CONFDIR in firewall.functions such that the per-if rules
are loaded.
* Set all rules executable.
-- Craig Box <packages@wiki.example.org> Wed, 6 Apr 2005 11:42:04 +1200
linuxserver-firewall (0.6) unstable; urgency=low
* Rebuild package due to loss of build source.
-- Craig Box <packages@wiki.example.org> Mon, 4 Apr 2005 14:56:45 +1200
linuxserver-firewall (0.5-REL3) unstable; urgency=low
* Updated to upstream REL3 version.
* Hardcoded more details (bad)
-- Craig Box <packages@wiki.example.org> Thu, 10 Jun 2004 11:47:25 +1200
linuxserver-firewall (0.3) unstable; urgency=low
* Added support for TCP ECN disabling and IP accounting
-- Craig Box <packages@wiki.example.org> Mon, 19 May 2003 19:40:53 +1200
linuxserver-firewall (0.2.2) unstable; urgency=low
* Now sets +x correctly on rulesets (makes running the firewall
much less painful)
-- Craig Box <packages@wiki.example.org> Mon, 19 May 2003 19:33:07 +1200
linuxserver-firewall (0.2) unstable; urgency=low
* Debian init script
* Moved classes.d and interfaces.d into /etc
-- Craig Box <packages@wiki.example.org> Mon, 5 May 2003 16:23:31 +1200
linuxserver-firewall (0.1-1) unstable; urgency=low
* Initial Release.
-- Craig Box <packages@wiki.example.org> Tue, 22 Apr 2003 04:32:24 +1200