[groff] 01/06: [docs]: Further cover portability of \*(.T, \n(.T.

[G. Branden Robinson]

gbranden pushed a commit to branch master
in repository groff.

commit 94c11995abb5a7fc5436f8fa457f4e21a032c76d
Author: G. Branden Robinson <g.branden.robinson@gmail.com>
AuthorDate: Mon Jun 7 19:57:01 2021 +1000

    [docs]: Further cover portability of \*(.T, \n(.T.
    
    Improve precision and fix an editing glitch noted by Dave Kemper.
    Thanks, Dave!
---
 doc/groff.texi       | 14 +++++++-------
 man/groff_diff.7.man | 45 +++++++++++++++++++++++----------------------
 2 files changed, 30 insertions(+), 29 deletions(-)

diff --git a/doc/groff.texi b/doc/groff.texi
index d45dc61..aad9fd9 100644
--- a/doc/groff.texi
+++ b/doc/groff.texi
@@ -15598,16 +15598,16 @@ GNU @code{troff} predefines a string @code{.T} 
containing the argument
 given to the @option{-T} command-line option, namely the current output
 device (for example, @samp{pdf} or @samp{utf8}).  The existence of this
 string is a common feature of post-CSTR@tie{}#54
-@code{troff}s@footnote{For example, DWB@tie{}3.3, Solaris, Heirloom
-Doctools, and Plan@tie{}9 @code{troff} all support it.} but valid values
-are specific to each implementation.
+@code{troff}s@footnote{DWB@tie{}3.3, Solaris, Heirloom Doctools, and
+Plan@tie{}9 @code{troff} all support it.} but valid values are specific
+to each implementation.
 
 @cindex output device usage register (@code{.T}), incompatibility with 
@acronym{AT&T} @code{troff}
-The (read-only) register @code{.T} is defined to be@tie{}1 if GNU
+The (read-only) register @code{.T} interpolates@tie{}1 if GNU
 @code{troff} is called with the @option{-T} command-line option, and
-zero otherwise.  This behavior differs from AT&T @code{troff}, which set
-this register to@tie{}1 when @code{nroff} was the formatter, was the
-formatter, and@tie{}0 otherwise.
+0@tie{}otherwise.  This behavior differs from AT&T @code{troff}, which
+interpolated@tie{}1 only if @code{nroff} was the formatter and was
+called with @option{-T}.
 
 @cindex @code{lf} request, incompatibilities with @acronym{AT&T} @code{troff}
 @acronym{AT&T} @code{troff} and other implementations handle the
diff --git a/man/groff_diff.7.man b/man/groff_diff.7.man
index 4f4683a..96633f4 100644
--- a/man/groff_diff.7.man
+++ b/man/groff_diff.7.man
@@ -4091,34 +4091,14 @@ namely the current output device
 or
 .BR utf8 ).
 .
-The existence of this string is a common feature of post-CSTR\~#54
-.IR troff s \" generic
-(for example,
-DWB\~3.3,
-Solaris,
-Heirloom Doctools,
-and Plan\~9
-.I troff \" foreign
-all support it)
-but valid values are specific to each implementation.
-.
-.
-.P
 The (read-only) register
 .B \[rs]n[.T]
-is defined to be\~1 if
+interpolates\~1 if
 .I \%@g@troff
 is called with the
 .B \-T
 command-line option,
-and\~0 otherwise.
-.
-This behavior differs from AT&T
-.IR troff , \" AT&T
-which set this register to\~1 when
-.I nroff \" AT&T
-was the formatter,
-and\~0 otherwise.
+and 0\~otherwise.
 .
 .
 .P
@@ -4868,6 +4848,27 @@ so choose a register name that is unlikely to collide 
with other uses.
 .
 .
 .P
+The existence of the
+.B .T
+string is a common feature of post-CSTR\~#54
+.IR troff s\[em]DWB\~3.3, \" others
+Solaris,
+Heirloom Doctools,
+and Plan\~9
+.I troff \" foreign
+all support it\[em]but valid values are specific to each implementation.
+.
+This behavior of the
+.B .T
+register differs from AT&T
+.IR troff , \" AT&T
+which interpolated\~1 only if
+.I nroff \" AT&T
+was the formatter and was called with
+.BR \-T .
+.
+.
+.P
 AT&T
 .I troff
 and other implementations handle