IRIG (Inter-Range Instrumentation Group)

IRIG (Inter-Range Instrumentation Group), in 1959, proposed a series of time code formats now known as IRIG or NASA time codes.

The best known IRIG standard is the IRIG timecode used to timestamp video, film, telemetry, radar, and other data collected at test ranges.

NENA-STA-026, NENA PSAP Master Clock Standard

Wikipedia definition