Add \*(Ai (ANSI) and \*(Px (POSIX) predefined strings, which are part of

groff's tmac.doc package.  Originally noted by Matthew Dempsky.
Feedback by Jason McIntyre, joerg@, and schwarze@.  Also add some
documentation about predefined strings, tweaked by schwarze@.

3 files changed, 12 insertions, 3 deletions

diff --git a/chars.c b/chars.c
index bd1edf6c..61569f88 100644
--- a/chars.c
+++ b/chars.c
@@ -41,7 +41,7 @@ struct	ln {
 #define CHARS_BOTH	 (CHARS_CHAR | CHARS_STRING)
 };
 
-#define	LINES_MAX	  351
+#define	LINES_MAX	  353
 
 #define CHAR(in, ch, code) \
 	{ NULL, (in), (ch), (code), CHARS_CHAR },
diff --git a/chars.in b/chars.in
index 5b7d99de..33ff760b 100644
--- a/chars.in
+++ b/chars.in
@@ -375,6 +375,8 @@ STRING("right-parenthesis",	")",		41)
 STRING("right-singlequote",	"\'",		8217)
 STRING("rp",			")",		41)
 STRING("Tm",			"(Tm)",		8482)
+STRING("Px",			"POSIX",	0)
+STRING("Ai",			"ANSI",		0)
 
 /* Lines. */
 CHAR("ba",			"|",		124)
diff --git a/mandoc_char.7 b/mandoc_char.7
index 3416de36..520d0a31 100644
--- a/mandoc_char.7
+++ b/mandoc_char.7
@@ -481,8 +481,13 @@ Greek letters:
 .It \e(ts    Ta \(ts        Ta sigma terminal
 .El
 .Sh PREDEFINED STRINGS
-These are not recommended for use, as they differ across
-implementations:
+Predefined strings are inherited from the macro packages of historical
+troff implementations.
+They are
+.Em not recommended
+for use, as they differ across implementations.
+Manuals using these predefined strings are almost certainly not
+portable.
 .Pp
 .Bl -column -compact -offset indent "Input" "Rendered" "Description"
 .It Em Input Ta Em Rendered Ta Em Description
@@ -512,6 +517,8 @@ implementations:
 .It \e*(>=   Ta \*(>=       Ta greater-than-equal
 .It \e*(aa   Ta \*(aa       Ta acute
 .It \e*(ga   Ta \*(ga       Ta grave
+.It \e*(Px   Ta \*(Px       Ta POSIX standard name
+.It \e*(Ai   Ta \*(Ai       Ta ANSI standard name
 .El
 .Sh NUMBERED CHARACTERS
 For backward compatibility with existing manuals,