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DITROFF(7)	       Miscellaneous Information Manual		    DITROFF(7)

       ditroff - classical device independent roff

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

       The  first  roff	system was written by Joe Osanna around	1973.  It sup-
       ported only two output devices, the nroff program  produced  text  ori-
       ented  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  cre-
       ating  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 Osanna'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 functional-
       ity  of	ditroff.   On  most  systems, the name troff is	used to	denote

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

       [CSTR #54]
	      The 1992 revision	of the Nroff/Troff User's Manual by J. F.  Os-
	      anna and Brian Kernighan,	see
	      Bell Labs	CSTR #54 <>.

       [CSTR #97]
	      A	Typesetter-independent TROFF by	Brian Kernighan	is the	origi-
	      nal 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	Free Software Foundation, Inc.

       This document is	distributed under the terms of the FDL (GNU Free Docu-
       mentation  License)  version  1.1 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 <>.

Groff Version 1.19	       14 February 2003			    DITROFF(7)


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