I'm researching about the possibility to specify a target version to go along carto documents to ensure their interpretation won't change over time. In doing this I found that mapnik-reference looks like trying to serve a similar need.
What I don't understand, though, is why mapnik-reference provides versions up to the patch level.
Does mapnik itself changes the language between patch level releases ?
I would expect to be able to reference "2.0" or "2.1" without the need to go as deep as "2.0.1".
Besides, latest mapnik-reference only has "2.0.1" as a version, thus lacking the latest stable release (2.0.2 at time of writing) and the former "2.0.0". I hope there's no need to add them, if the "2.0" route is taken instead.
Yes, in rare cases users may request a parameter be backported and added to a stable/patch level release. If this ever is done then mapnik-reference is an important place to capture that. In the case of the 2.0.x series the only addition was marker-ignore-placement which was added at 2.0.1 (mapnik/mapnik#1135 | mapnik/mapnik#1163).