There may be one changelog for each catkin package
The changelog file, CHANGELOG.rst, must reside in the root of a package as a peer to the package.xml file
The changelog will be written in RST (with some restrictions on content)
The changelog will be parsed and injected into debian packages by bloom
The changelog will be parsed and injected into the wiki by rosdoc-lite
The changelog will have sections with titles like `<major.minor.patch> (<YYYY-MM-DD [HH:MM[:SS[ TZOFFSET]]])`

There are more diverse examples in the REP, but here is an example CHANGELOG.rst file:

https://github.com/ros-infrastructure/bloom/blob/master/CHANGELOG.rst

As of catkin_pkg 0.1.11 there is a tool called `catkin_test_changelog` which will parse your CHANGELOG.rst and warn you about any ignored sections.

You can always do a simple date, like 2013-04-10, but there is a convenient git command to get the full timestamps of tags:

git log --tags --simplify-by-decoration --pretty="format:%ai %d"

If you are interested in this REP please have a look at the full REP:

http://ros.org/reps/rep-0132.html

And then vote or comment on the activation pull request:

https://github.com/ros-infrastructure/rep/pull/38

If you have concerns or comments about the REP, please read the "Concerns" section of REP and the mailing list posts in the reference section before bringing up something which has already been discussed and then comment on the above pull request.

Thanks for your time,