A) SMPTE 12M - A digital code recorded by video and audio magnetic tape recorders, identifying each frame with a unique and complete address. Unassigned bits permit limited production identification. The time and control code was developed for 525-line/60- field systems. An international version compatible with SMPTE 12M is described in IEC Publication 461. Variants have evolved for 24- and 25- frame systems.

b) Cinematography - A digital code format applicable to motion-picture film at 24, 25, or 30 frames/sec. Two types are described: Type C, a continuous code very similar to SMPTE 12M and IEC Publication 461 to be read from continuously moving film, and Type B, a non-continuous block-type code for intermittently moving film, but still decodable with the same type of electronic equipment used to read Type C.