[docs]: Fix Savannah #63812.

* doc/groff.texi (Operators in Conditionals):
* man/groff.7.in (Conditional expressions): Clarify how the output
  comparison operator is recognized.

Fixes <https://savannah.gnu.org/bugs/?63812>.  Thanks to John Gardner
for the report.

ANNOUNCE: Update bug counts.

1 files changed, 11 insertions, 0 deletions

diff --git a/doc/groff.texi b/doc/groff.texi
index 5c4af4fc9..7e300dbef 100644
--- a/doc/groff.texi
+++ b/doc/groff.texi
@@ -12571,8 +12571,19 @@ certain other @code{troff} implementations.@footnote{This refers to
 @code{vtroff}, a translator that would convert the C/A/T output from
 early-vintage @acronym{AT&T} @code{troff} to a form suitable for
 Versatec and Benson-Varian plotters.}
+@end table
+
+If the first argument to an @code{if}, @code{ie}, or @code{while}
+request begins with a non-alphanumeric character apart from @code{!}
+(see below); it performs an @slanted{output comparison test}.
+@footnote{Strictly, letters not otherwise recognized @emph{are} treated
+as output comparison delimiters.  For portability, it is wise to avoid
+using letters not in the list above; for example, Plan@tie{}9
+@code{troff} uses @samp{h} to test a mode it calls @code{htmlroff}, and
+GNU @code{troff} may provide additional operators in the future.}
 
 @cindex output comparison operator
+@table @code
 @item @code{'}@var{xxx}@code{'}@var{yyy}@code{'}
 True if formatting the comparands @var{xxx} and @var{yyy} produces the
 same output commands.  The delimiter need not be a neutral apostrophe: