VSPSCC files are used to prevent simultaneous editing of the same project file by multiple developers. Unlike Subversion, which will allow multiple developers to edit a file and then merge the changes, this version of source control forces the developers to check out the file and prevents changes by any user which does not have it checked out. Also unlike other source controls, VSPSCC files allow the entire file to be checked out from a single location instead of checking out only the changes between your file version and the one contained on the server.