[docs]: Fix Savannah #68216.

[docs]: Re-re-christen 'ESCAPE_AMPERSAND' ('\&').  Now call it a
(non-transparent) "dummy character".  Also rechristen
'ESCAPE_RIGHT_PARENTHESIS', ('\)') as the "transparent dummy character";
it has no impact on sentence-ending detection.

* doc/groff.texi:
* doc/meref.me.in:
* man/groff.7.man:
* man/groff_diff.7.man:
* man/roff.7.man:
* src/preproc/refer/refer.1.man:
* tmac/groff_man.7.man.in: Do it.

Fixes <https://savannah.gnu.org/bugs/?62816>.  Thanks to Dave Kemper for
the report and to the groff mailing list for the vigorous discussion.  I
don't expect my solution to please everyone.

Also update references to the \& escape sequence in comments.

ANNOUNCE: Update bug counts.

2 files changed, 14 insertions, 13 deletions

diff --git a/tmac/an.tmac b/tmac/an.tmac
index 7ab3ccae1..d67db938e 100644
--- a/tmac/an.tmac
+++ b/tmac/an.tmac
@@ -819,11 +819,11 @@ contains unsupported escape sequence
 .\"
 .\" Implementation notes:
 .\"
-.\" We always emit a non-printing input break \& before the first
-.\" argument.  This is necessary only when the calling man page is in
-.\" compatibility mode; it works around the surprising AT&T semantics of
-.\" \f escapes at the beginning of an input line.  See "Implementation
-.\" differences" in groff_diff(7) or the groff Texinfo manual.
+.\" We always emit a dummy character \& before the first argument.  This
+.\" is necessary only when the calling man page is in compatibility
+.\" mode; it works around the surprising AT&T semantics of \f escapes at
+.\" the beginning of an input line.  See "Implementation differences" in
+.\" groff_diff(7) or the groff Texinfo manual.
 .\"
 .\" The italic correction escapes can be visually confusing.  We apply
 .\" the following rules, always on the same input line.
diff --git a/tmac/groff_man.7.man.in b/tmac/groff_man.7.man.in
index 4b10d3282..971a1c609 100644
--- a/tmac/groff_man.7.man.in
+++ b/tmac/groff_man.7.man.in
@@ -696,7 +696,7 @@ or
 .B ?\&
 followed by multiple spaces can change.
 .
-Use the non-printing input break escape sequence
+Use the dummy character escape sequence
 .B \(rs&
 before the spaces.
 .
@@ -1222,7 +1222,7 @@ see subsection \(lqPortability\(rq below.
 .
 .
 .IP \(bu
-The non-printing input break escape sequence
+The dummy character escape sequence
 .B \e&
 follows the ellipsis when further text will follow after space on the
 output line,
@@ -2534,7 +2534,7 @@ or Documenter's Workbench
 .
 .TP
 .B \e&
-Non-printing input break.
+Dummy character.
 .
 Insert at the beginning of an input line to prevent a dot or apostrophe
 from being interpreted as the beginning of a
@@ -4055,7 +4055,7 @@ Since dots both begin control lines and are candidate end-of-sentence
 characters,
 however,
 it is sometimes necessary to prefix and/or suffix an ellipsis with the
-non-printing input break escape sequence
+dummy character escape sequence
 .BR \[rs]& .
 .
 That fact stands even if a string is defined to contain the sequence;
@@ -4071,9 +4071,9 @@ but not always.)
 A hypothetical string
 .B EL
 that contained an ellipsis,
-but not the trailing input break,
-would then need to be suffixed with
-.B \[rs]&
+but not the trailing dummy character
+.BR \[rs]& ,
+would then need to be suffixed with the latter
 when not ending a sentence.
 .
 .
@@ -4119,7 +4119,8 @@ In syntax synopses,
 missing ellipses can cause great confusion.
 .
 Dots and space are universally supported.
-.\" XXX: Does an unconditional _preceding_ input break cause problems?
+.\" XXX: Does an unconditional _preceding_ dummy character cause
+.\" problems?
 _endif()dnl
 .
 .