groff: gtroff Output
8.1 'gtroff' Output
===================
This section describes the intermediate output format of GNU 'troff'.
This output is produced by a run of 'gtroff' before it is fed into a
device postprocessor program.
As 'groff' is a wrapper program around 'gtroff' that automatically
calls a postprocessor, this output does not show up normally. This is
why it is called "intermediate". 'groff' provides the option '-Z' to
inhibit postprocessing, such that the produced intermediate output is
sent to standard output just like calling 'gtroff' manually.
Here, the term "troff output" describes what is output by 'gtroff',
while "intermediate output" refers to the language that is accepted by
the parser that prepares this output for the postprocessors. This
parser is smarter on whitespace and implements obsolete elements for
Output-Footnote-1::)
The main purpose of the intermediate output concept is to facilitate
the development of postprocessors by providing a common programming
interface for all devices. It has a language of its own that is
completely different from the 'gtroff' language. While the 'gtroff'
language is a high-level programming language for text processing, the
intermediate output language is a kind of low-level assembler language
by specifying all positions on the page for writing and drawing.
The intermediate output produced by 'gtroff' is fairly readable,
while output from AT&T 'troff' is rather hard to understand because of
strange habits that are still supported, but not used any longer by
'gtroff'.
Menu