Source Code Control System (SCCS) is a version control system designed to track changes in source code and other text files during the development of a piece of software. This allows the user to retrieve any of the previous versions of the original source code and the changes which are stored. It was originally developed at Bell Labs beginning in late 1972 by Marc Rochkind for an IBM System/370 computer running OS/360. A characteristic feature of SCCS is the sccsid string that is embedded into source code, and automatically updated by SCCS for each revision. This example illustrates its use in the C programming language: static char sccsid[] = "@(#)ls.c 8.1 (Berkeley) 6/11/93"; This string contains the file name, date, and can also contain a comment. After compilation, the string can be found in binary and object files by looking for the pattern @(#) and can be used to determine which source code files were used during compilation. The what command is available to automate this search for version strings. History In 1972, Marc Rochkind developed SCCS in SNOBOL4 at Bell Labs for an IBM System/370 computer running OS/360 MVT. He rewrote SCCS in the C programming language for use under UNIX, then running on a PDP-11, in 1973. The first publicly released version was SCCS version 4 from February 18, 1977. It was available with the Programmer's Workbench (PWB) edition of the operating system. Release 4 of SCCS was the first version that used a text-based history file format, earlier versions did use binary history file formats. Release 4 was no longer written or maintained by Marc Rochkind. Subsequently, SCCS was included in AT&T's commercial System III and System V distributions. It was not licensed with 32V, the ancestor to BSD. The SCCS command set is now part of the Single UNIX Specification. SCCS was the dominant version control system for Unix until later version control systems, notably the RCS and later CVS, gained more widespread adoption. Today, these early version control systems are generally considered obsolete, particularly in the open-source community, which has largely embraced distributed version control systems. However, the SCCS file format is still used internally by a few newer version control programs, including BitKeeper and TeamWare. The latter is a frontend to SCCS. Sablime has been developed from a modified version of SCCS but uses a history file format that is incompatible with SCCS. The