that teletext often carries important information, such as subtitles in various languages and for the hearing impaired viewers, as well as, in the future, coded sound commentary for the visual impaired viewers and similar ancillary programme-related servi
ITU-R BR.1218-1-2001 history
2001ITU-R BR.1218-1-2001 Recording of Ancillary Data on Digital Recorders for Consumer Use