Projector is an easy-to-use built-in source code management system for controlling and accounting for all changes to software or documentation over the life of a project. The source is stored in a revision file so that any version of the software may be built on command. Projector controls access to the files so that only one person is modifying a file at a time. Projector keeps track of who has modified the files and why each modification was done. Projector is part of the MPW Shell.