Concurrent Versions System (CVS) is a freeware version control system that is widely used by freeware developers including those in high energy physics. It is used by the CERN and Fermilab computing divisions and by the following physics collaborations: ATLAS, CMS, SDSS, NuTeV, CLEO, and BaBar. Now it is also being used by CDF, D0 and BTeV.
Additional information can be found at: