Like SMPTE 259, SMPTE 292 supports the  SMPTE 291 standard for ancillary data. Ancillary data is provided as a standardized transport for non-video payload within a serial digital signal; it is used for things such as embedded audio, closed captions, timecode, and other sorts of metadata.
SMPTE 259 and SMPTE 292 both support the SMPTE 291 standard for ancillary data. Ancillary data is a standardized method for carrying non-video information within a digital signal, including things like embedded audio, closed captions, timecode, and other metadata.