Version Control
===============
"Version control systems" are packages that can record multiple
versions of a source file, usually storing the unchanged parts of the
file just once. Version control systems also record history information
such as the creation time of each version, who created it, and a
description of what was changed in that version.
The Emacs version control interface is called VC. Its commands work
with three version control systems--RCS, CVS, and SCCS. The GNU
project recommends RCS and CVS, which are free software and available
from the Free Software Foundation. We also have free software to
replace SCCS, known as CSSC; if you are using SCCS and don't want to
make the incompatible change to RCS or CVS, you can switch to CSSC.