[groff] 28/38: roff(7): Recast preprocessor discussion.

[G. Branden Robinson]

gbranden pushed a commit to branch master
in repository groff.

commit 59537665ab5be81fcb4bd6ce70b00f12a5d709c8
Author: G. Branden Robinson <g.branden.robinson@gmail.com>
AuthorDate: Thu Sep 1 01:45:33 2022 -0500

    roff(7): Recast preprocessor discussion.
---
 man/roff.7.man | 76 ++++++++++++++++++++++++++++++----------------------------
 1 file changed, 39 insertions(+), 37 deletions(-)

diff --git a/man/roff.7.man b/man/roff.7.man
index 668849019..4a23bc7d5 100644
--- a/man/roff.7.man
+++ b/man/roff.7.man
@@ -1532,8 +1532,8 @@ only programmers of macro packages need a substantial 
command of it.
 .
 A
 .I roff
-preprocessor is any program that generates output that syntactically
-obeys the rules of the
+preprocessor is any program generating output that syntactically obeys
+the rules of the
 .I roff
 formatting language.
 .
@@ -1542,58 +1542,60 @@ into
 .I roff
 code when run through the preprocessor program.
 .
-Parts written in these languages may be included within a
+Portions of the document written in these languages are bracketed by
+tokens that look like
 .I roff
-document; they are identified by special
-.I roff
-requests or macros.
+macro calls.
 .
-Each document that is enhanced by preprocessor code must be run
-through all corresponding preprocessors before it is fed into the
-actual
 .I roff
-formatter program, for the formatter just ignores all alien code.
+preprocessor programs transform only the regions of the document
+inteded for them.
 .
-The preprocessor programs extract and transform only the document
-parts that are determined for them.
+Each document thus enhanced by preprocessor code must be run through the
+corresponding preprocessors before the formatter processes it.
 .
+Some preprocessors produce input intended for interpretation by another
+preprocessor;
+for example,
+.I chem \" generic
+produces
+.I pic \" generic
+input.
 .
-.P
-There are a lot of free and commercial
-.I roff
-preprocessors.
-.
-Some of them aren't available on each system, but there is a small
-set of preprocessors that are considered as an integral part of each
+Preprocessors must consequently be run in an appropriate order;
+.MR groff @MAN1EXT@
+handles this automatically for all preprocessors supplied by the GNU
 .I roff
 system.
 .
-The classical preprocessors are
 .
-.RS
-.TS
-tab (@);
-lb l.
-tbl@for tables.
-eqn@for mathematical formulae.
-pic@for drawing diagrams.
-refer@for bibliographic references.
-soelim@for including macro files from standard locations.
-chem@for drawing chemical formul\[ae].
-.TE
-.RE
+.P
+GNU
+.I roff
+provides several preprocessors,
+including
+.IR @g@eqn ,
+.IR @g@grn ,
+.IR @g@pic ,
+.IR @g@tbl ,
+.IR @g@refer ,
+and
+.IR @g@soelim .
 .
 .
 .P
-Other known preprocessors that are not available on all systems
-include
+Other preprocessors for
+.I roff
+systems are known.
+.
 .
 .RS
 .TS
 tab (@);
-lb l.
-grap@for constructing graphical elements.
-grn@for including \fBgremlin\fR(1) pictures.
+Li L.
+dformat@depicts data structures;
+grap@constructs statistical charts; and
+ideal@draws diagrams using a constraint-based language
 .TE
 .RE
 .