These are mostly poll results, old plans that got implemented and documented elsewhere.
There were a serias on features implemented until late 2016. The original idea was that svn commits were tagged in the log so mainline would have easier job pciking revisions for merging a specific feture. These files were the documentation of the current state of those features - sort of a datasheet for eahc feature. (Mainline didn't merge much, keeping them in trunk/ makes no sense).