Rcs
- ci(1) check in RCS revisions
- co(1) check out RCS revisions
- ident(1) identify RCS keyword strings in files
- merge(1) three-way file merge
- rcs(1) change \*o attributes
- rcsclean(1) clean up working files
- rcsdiff(1) compare RCS revisions
- rcsfile(5) \*o format
- rcsmerge(1) merge RCS revisions
- rlog(1) print log messages and other information about \*os