concurrent versions system

noun
  1. computing a system that allows more than one person to work on the same file at the same time, merging their changes but keeping records of the different versions
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012