A CM file is a file with the `.cm` extension, but the extension is used by more than one type of software. CM file compatibility is a CLEO Custom Mission file for Grand Theft Auto: San Andreas. These files contain custom missions or gameplay modifications and are commonly created or edited with tools such as Sanny Builder.CM File as a GTA San Andreas Custom MissionIn GTA: San Andreas modding, a `.cm` file contains a custom CLEO mission. It is similar to a CLEO `.cs` script, but it is specifically saved as a mission. To use one, it is normally placed inside the game's CLEO folder, assuming CLEO is installed. Sanny Builder is commonly used to create and modify these files.CM File as a Cable Modem Configuration FileThe `.cm` extension can also represent a Cable Modem Configuration file. These configuration files may contain parameters supplied by an Internet service provider, such as permitted upstream and downstream speeds or firmware-related instructions. They are generally intended for the modem itself rather than for users to manually open or edit.Other Less Common CM File TypesSome applications have also used `.cm` for specialized data such as compiled macros, software modules, puzzles, or licensing-related files. Because several unrelated formats can share the same extension, the program that created the file is important when determining what a particular CM file contains.How to Open a CM FileFor a GTA San Andreas CM file, programs such as Sanny Builder, CLEO-compatible tools, or GTA: San Andreas itself may be appropriate. A cable-modem CM file normally should not be manually opened or modified because it is intended to be processed by modem equipment.If you're preparing another FileMagic article, I can also turn this into the same Header → one paragraph → Header 2 → one paragraph format you used for the CHD and CHESSTITAN articles.