The CCITT,considering,on the one hand,(a) that the receiving portion of the sending end of the synchronous system can be linked to a start-stopreceiver operating at the nominal modulation rate of 50 bauds.
ITU-T S.12-1988 Referenced Document
ITU-T S.3 Transmission Characteristics of the Local End with Its Termination (ITA2) - Telegraph Services Terminal Equipment (Study Group IX) 3 pp*, 1989-01-01 Update
ITU-T S.12-1988 history
1988ITU-T S.12-1988 CONDITIONS THAT MUST BE SATISFIED BY SYNCHRONOUS SYSTEMS OPERATING IN CONNECTION WITH STANDARD 50-BAUD TELEPRINTER CIRCUITS