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 Osanna 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. Kernighans version marks what is known as classical troff today. In order to distinguish it from Osannas 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 Kernighans multi-device troff. The distinction between troff and ditroff isnt 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.
| ||The 1992 revision of theNroff/Troff Users Manual byJ. F. Osanna and"Brian Kernighan", see|
"Bell Labs CSTR~#54" .
| ||A Typesetter-independent TROFF byBrian 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 ofditroff. |
| ||The GNU roff program and pointers to all documentation around groff.|
| ||The groff version of the intermediate output language, the basis formulti-devicing.|