CGMS

CGMS

Copy Generation Management System - Analog (CGMS-A) is a copy protection mechanism for analog television signals. It consists of a waveform inserted into the non-picture Vertical Blanking Interval (VBI) of an analogue video signal. If a compatible recording device (for example, a DVD recorder) detects this waveform, it may block or restrict recording of the video content.

It is not the same as the Broadcast flag, which is designed for use in digital television signals, although the concept is the same. There is a digital form of CGMS specified as CGMS-D which is required by the DTCP ("5C") protection standard.