DITROFF(7)DITROFF(7)NAMEditroff - 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 Ossanna 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 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 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‐
The 1992 revision of the Nroff/Troff User's Manual by J. F.
Ossanna and Brian Kernighan, see Bell Labs CSTR #54 ⟨http://
A Typesetter-independent TROFF by Brian Kernighan is the origi‐
nal documentation of the first multi-device troff (ditroff), see
Bell Labs CSTR #97 ⟨http://cm.bell-labs.com/cm/cs/cstr/
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
Copyright (C) 2001, 2002, 2004, 2007-2009, 2012 Free Software Founda‐
This document is distributed under the terms of the FDL (GNU Free Docu‐
mentation 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 ⟨http://www.gnu.org/copyleft/fdl.html⟩.
This document is part of groff, the GNU roff distribution. It was
written by Bernd Warken ⟨email@example.com⟩ and is main‐
tained by Werner Lemberg ⟨firstname.lastname@example.org⟩.
Groff Version 1.22.2 7 February 2013 DITROFF(7)