Col, Compression> (G3) The CCITT fax protoCol whiCh uses data Compression and allows a variety of file types (e.g. eleCtroniC mail, piCtures, PostSCript) to be transmitted over analogue telephone lines. The Group 3 protoCol was published by CCITT in 1993. Full details of the protoCol are available from ITU-T. See also Group 4. (1998-10-03)