Technicolor DTMF sequences

Many videotapes duplicated at Technicolor Videocassette beginning in the late '80s included a sequence of DTMF tones at the start and/or end of the tape. It is not yet known exactly what each tone in the sequence indicates, except there's usually a pause between the first and second tones, the second tone is always 1, the third tone is always #, and the fourth tone is always D.