SMPTE 256M – Television – Specifications for Video Tape Leader
This standard specifies the minimum requirements for the content and duration of signals recorded prior to the start of the recorded program material to permit setup and adjustment of equipment for optimum performance during reproduction.The standard also specifies a visual and aural countdown sequence to facilitate program cueing and specifies the duration of video tape that precedes and follows the recorded material to provide the minimum lengths of tape required to ensure proper threading in video tape systems which do not employ tape cassettes.
