Binary package “rcs” in ubuntu lucid
The GNU Revision Control System
The Revision Control System (RCS) manages multiple
revisions of files. RCS automates the storing, retrieval,
logging, identification, and merging of revisions. RCS is
useful for text that is revised frequently, for example
programs, documentation, graphics, papers, and form letters.
Note: this package contains certain general-purpose commands
(such as merge or ident) which may used by other programs
installed on your system.