CM is a file format native to a computer game titled Grand Theft Auto San Andreas. CM is a file that contains custom mission or map created by user. CM files are created using GTA modding tool Sanny Builder.

CM files are created in process of decompiling main.scm file, which stores all main GTA scripts. Those scripts can then be edited and added to the game. Sanny Builder uses CLEO library that contains codes which can be used for creating custom scripts.