CSSC is the GNU Project's replacement for SCCS.  SCCS is a proprietary suite
of tools which is provided with most commercial versions of Unix.  The purpose
behind CSSC is to provide a work-alike for SCCS which can be used on the
various Free versions of Unix.

SCCS was the only major form of source code control on Unix platforms for many
years, until RCS came along.  SCCS was an effective method for small projects,
but these days it is less popular, particularly for projects involving large
numbers of files.  A certain amount of old software is still in SCCS form, and
CSSC is designed to retrieve that software.  Once retrieved, it is recommended
to bring the source under the control of a more modern source code control
system, such as git or Apache Subversion.

However, SCCS (and CSSC) is still perfectly adequate for small projects.  For
example, if you are familiar with SCCS, it is not unreasonable to control the
files in /etc and /usr/local/etc on your private FreeBSD machine with CSSC.

WWW: http://www.gnu.org/software/cssc/