An old tool used to format Unix (and Tcl/Tk) man pages. Alas, it is one of the less well-known formats about despite its widespread use even now. The sister tool troff produces rather pretty output, similar in quality to LaTeX. [groff] is the most common modern implementation, and can produce fine nroff-level output even to terminals, so long as they are UNICODE-enabled and are using a suitable font.

The basic format is documented in CSTR#54, which is downloadable (as gzipped PostScript) from http://cm.bell-labs.com/cm/cs/cstr.html

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