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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 isnt 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 Users 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

              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  (C)  2001,  2002,  2004,  2007,  2008,  2009  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