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          ditroff - classical device-independent roff

          The name ditroff refers to a historical development stage of
          the roff(7) text processing system.  In roff systems extant
          today, the name troff is a synonym for ditroff.

          Early versions of roff by Joe Ossanna generated two programs
          from the same sources, using conditional compilation to dis-
          tinguish them.  nroff produced text-oriented TTY output,
          while troff generated graphical output for exactly one out-
          put device, the Wang Graphic Systems CAT phototypesetter.

          In 1979, Brian Kernighan rewrote troff to support more
          devices by creating an intermediate output format for troff
          that could be fed into postprocessor programs which actually
          do the printout on the device.  Kernighan's version marks
          what is known as lqclassical troffrq today.  In order to dis-
          tinguish it from Ossanna's original version, it was called
          ditroff (device independent t on some systems, though this
          naming isn't mentioned in the classical documentation.

          Today, all existing roff systems are based on Kernighan's
          multi-device troff. The distinction between troff and
          ditroff is no longer necessary; each modern troff provides
          the complete functionality of ditroff.

          The easiest way to use ditroff is via the GNU roff system,
          groff. The groff(1) program is a wrapper around (di)troff
          that automatically handles device postprocessing.

          This document was written by Bernd Warken

               refers to the 1992 revision of the Nroff/Troff User's
               Manual by J. F. Ossanna and Brian Kernighan.

               refers to A Typesetter-independent TROFF, by Brian Ker-
               nighan and is the original documentation of the first
               multi-device troff (ditroff).

               provides a history and conceptual overview of roff sys-

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               describes the GNU implementation of (di)troff.

               documents the GNU roff program and includes pointers to
               further documentation about groff.

               describes the groff version of the intermediate output
               language, the basis for multi-device output.

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