Copy Generation Management System, a method for controlling copying of DVD-Video discs. It allows only a first-generation copy to be made. The player embeds information such as "Copy free," "First generation only OK" or "Copy not possible" in the playback signal and outputs it together with the latter, and the recorder detects it.

Copy Guard Management System. A method of preventing copies or controlling the number of sequential copies allowed. CGMS/A is added to an analog signal (such as line 21 of NTSC). CGMS/D is added to a digital signal, such as IEEE 1394.

Content Guard Management System. Copy protection for DVDs that will permit a limited number of copies to be made.

Coordination Group for Meteorological Satellites

Continuous Glucose Monitoring System - a system for recording your glucose level continuously. Launched by MiniMed in 2000.