Society of Motion Picture and Television Engineers. A United States organization, with international branches, which includes representatives of broadcasters, manufacturers and individuals working in the film and television industry. Within its structure it has a number of committees that make recommendations (RP 125 for example) to the ITU-R and to ANSI in the USA.
Here are just a few of the many standards and recommendations issued by SMPTE:
259M SDI for 4:2:2 and 3fsc
272M AES/EBU audio and aux data into video ancillary space
294M TV format, 720 x 483 at 59.94P Hz
305M SDTI Serial Data Transport Interface
424M 3 Gb/s signal/data serial interface