An extenSIon of the ITU-TV.42 standard modemprotocol to included compresSIon uSIng a Lempel-Ziv related technique, which detects frequently occurring character strings and replaces them with tokens. This is SImilar to the Unixcompress utility. Typical compresSIon for text is 50% or better with nearly 20% gain from synchronous converSIon this gives reduces transmisSIon time by almost 60%. [Details? On-line spec?] (2004-08-02)