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       ditroff - classical device independent roff


       The  name ditroff once marked a development level of the troff text processing system.  In
       actual roff(7) systems, the name troff is used as a synonym for ditroff.

       The first roff system was written by Joe Ossanna  around  1973.   It  supported  only  two
       output  devices,  the  nroff  program  produced  text oriented tty output, while the troff
       program generated graphical output for exactly one output device, the Wang Graphic Systems
       CAT typesetter.

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

       Today, any  existing  roff  system  is  based  on  Kernighan's  multi-device  troff.   The
       distinction  between  troff  and ditroff isn't necessary any longer, for each modern troff
       provides already the complete functionality of ditroff.  On most systems, the  name  troff
       is used to denote ditroff.

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


       [CSTR #54]
              The 1992 revision of the Nroff/Troff User's Manual  by  J.  F.  Ossanna  and  Brian
              Kernighan, see Bell Labs CSTR #54 ⟨⟩.

       [CSTR #97]
              A  Typesetter-independent TROFF by Brian Kernighan is the original documentation of
              the first multi-device troff (ditroff), see Bell  Labs  CSTR  #97  ⟨http://cm.bell-

              This document gives details on the history and concepts of roff.

              The actual implementation of ditroff.

              The GNU roff program and pointers to all documentation around groff.

              The  groff  version  of  the  intermediate  output  language,  the basis for multi-


       Copyright (C) 2001, 2002, 2004, 2007-2009, 2012 Free Software Foundation, Inc.

       This document is distributed under the terms of the FDL (GNU Free  Documentation  License)
       version  1.3  or  later.  You should have received a copy of the FDL on your system, it is
       also available on-line at the GNU copyleft site ⟨⟩.

       This document is part of groff, the GNU roff distribution.  It was written by Bernd Warken
       ⟨⟩ and is maintained by Werner Lemberg ⟨⟩.