[program] SQ was a program used in the early 1980s on both DOS and CP/M computer systems to compress files so they use less space. Files compressed by SQ are identified by changing the middle initial of the extension to `Q`, so that text files ended with the extension .TQT, executable files ended with the extension .CQM or .EQE, documents w... Found on http://en.wikipedia.org/wiki/SQ_(program)