[groff] 12/12: [docs]: Update discussion of AT&T/GNU differences.

[G. Branden Robinson]

gbranden pushed a commit to branch master
in repository groff.

commit d67b7d7a8b82a3474ab133531e70f0499babf937
Author: G. Branden Robinson <g.branden.robinson@gmail.com>
AuthorDate: Fri Feb 2 19:47:10 2024 -0600

    [docs]: Update discussion of AT&T/GNU differences.
    
    Motivate the material a bit more.  Get the organization a bit more
    parallel, but to continue down this road will require relocation of
    text.
---
 doc/groff.texi       | 25 +++++++++++++++----------
 man/groff_diff.7.man | 30 ++++++++++++++++++++----------
 2 files changed, 35 insertions(+), 20 deletions(-)

diff --git a/doc/groff.texi b/doc/groff.texi
index fef257741..04aa89d52 100644
--- a/doc/groff.texi
+++ b/doc/groff.texi
@@ -17457,20 +17457,25 @@ extension requests, @code{open}, @code{opena}, and 
@code{pso}.
 @cindex compatibility mode
 @cindex mode, compatibility
 
+Some implementation differences between GNU and @acronym{AT&T}
+@command{troff}s are thought too important to neglect; @code{groff}
+therefore makes available a @dfn{compatibility mode} in an effort to
+keep documents prepared for AT&T @command{troff} rendering well.
+
 @cindex long names
 @cindex names, long
 @cindex @code{\*}, incompatibilities with @acronym{AT&T} @code{troff}
 @cindex @code{\n}, incompatibilities with @acronym{AT&T} @code{troff}
-Long identifier names may be GNU @code{troff}'s most obvious innovation.
-@acronym{AT&T} @code{troff} interprets @samp{.dsabcd} as defining a
-string @samp{ab} with contents @samp{cd}.  Normally, GNU @code{troff}
-interprets this as a call of a macro named @code{dsabcd}.
-@acronym{AT&T} @code{troff} also interprets @samp{\*[} and @samp{\n[} as
-an interpolation of a string or register, respectively, named @samp{[}.
-In GNU @code{troff}, however, the @samp{[} is normally interpreted as
-delimiting a long name.  In compatibility mode, GNU @code{troff}
-interprets names in the traditional way; they thus can be two characters
-long at most.
+Identifier names of arbitrary length may be GNU @code{troff}'s most
+obvious innovation.  @acronym{AT&T} @code{troff} interprets
+@samp{.dsabcd} as defining a string @samp{ab} with contents @samp{cd}.
+Normally, GNU @code{troff} interprets this as a call of a macro named
+@code{dsabcd}.  @acronym{AT&T} @code{troff} also interprets @samp{\*[}
+and @samp{\n[} as an interpolation of a string or register,
+respectively, named @samp{[}.  In GNU @code{troff}, however, the
+@samp{[} is normally interpreted as delimiting a long name.  In
+compatibility mode, GNU @code{troff} interprets names in the traditional
+way; they thus can be two characters long at most.
 
 @DefreqList {cp, [@Var{n}]}
 @DefregListEndx {.C}
diff --git a/man/groff_diff.7.man b/man/groff_diff.7.man
index 8700e9c9d..81c20fdf2 100644
--- a/man/groff_diff.7.man
+++ b/man/groff_diff.7.man
@@ -5298,7 +5298,7 @@ to the standard error stream.
 .
 .
 .\" ====================================================================
-.SH "Implementation differences"
+.SH "Other differences"
 .\" ====================================================================
 .
 .\" TODO: Resync with the node of this name in our Texinfo manual.
@@ -5366,8 +5366,23 @@ GNU
 has no such restriction.
 .
 .
+.\" ====================================================================
+.SH "Compatibility mode"
+.\" ====================================================================
+.
+Some implementation differences between GNU and AT&T
+.IR troff s \" generic
+are thought too important to neglect;
+.I groff
+therefore makes available a
+.I "compatibility mode"
+in an effort to keep documents prepared for AT&T
+.I troff \" AT&T
+rendering well.
+.
+.
 .P
-Long names may be GNU
+Identifier names of arbitrary length may be GNU
 .IR troff 's \" GNU
 most obvious innovation.
 .
@@ -5556,7 +5571,7 @@ See section \[lq]Miscellaneous\[rq] above.
 .
 .
 .P
-In compatibility mode,
+Further,
 the escape sequences
 .BR \[rs]f ,
 .BR \[rs]H ,
@@ -5566,13 +5581,8 @@ the escape sequences
 .BR \[rs]s ,
 and
 .B \[rs]S
-are transparent at the beginning of an input line for the purpose of
-recognizing a control character,
-because they modify formatter state
-.RB ( \[rs]R )
-or properties of the environment
-(the rest)
-and therefore do not create output nodes.
+are transparent at the beginning of an input line only in compatibility
+mode.
 .
 .
 .P