Troff is a UNIX formatting and phototypesetting program, written originally in PDP-11 assembler and then in barely-structured early C by the late Joseph Ossanna, modelled after the earlier ROFF which was in turn modelled after Multics' RUNOFF by Jerome Saltzer (that name came from the expression 'to run off a copy'). A companion program, 'nroff', formats output for terminals and line printers. In 1979, Brian Kernighan modified TROFF so that it could drive phototypesetters other than the Graphic Systems CAT. The success of TeX and desktop publishing systems have reduced troff's relative importance. Research Troff