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 http://

   [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-labs.com/cm/

          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

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


   Copyright  2001-2014 Free Software Foundation, Inc.

   This file is part of groff, the GNU roff type-setting system.

   Permission  is  granted to copy, distribute and/or modify this document
   under the terms of the GNU Free Documentation License, Version  1.3  or
   any  later  version  published by the Free Software Foundation; with no
   Front-Cover Texts, and with no Back-Cover Texts.

   A copy of the Free Documentation License is included as a  file  called
   FDL  in  the  main  directory  of  the groff source package, it is also
   available  on-line  at  the  GNU  copyleft  site   http://www.gnu.org/


   It  was  written  by Bernd Warken groff-bernd.warken-72@web.de and is
   maintained by Werner Lemberg wl@gnu.org.


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