===================================================================
RCS file: /cvs/mandoc/mdoc.7,v
retrieving revision 1.104
retrieving revision 1.105
diff -u -p -r1.104 -r1.105
--- mandoc/mdoc.7	2010/05/14 15:17:23	1.104
+++ mandoc/mdoc.7	2010/05/14 16:02:29	1.105
@@ -1,4 +1,4 @@
-.\"	$Id: mdoc.7,v 1.104 2010/05/14 15:17:23 kristaps Exp $
+.\"	$Id: mdoc.7,v 1.105 2010/05/14 16:02:29 kristaps Exp $
 .\"
 .\" Copyright (c) 2009 Kristaps Dzonsons <kristaps@bsd.lv>
 .\"
@@ -1960,6 +1960,12 @@ and
 .Sx \&Ex
 macros were stipulated only to occur in certain manual sections.
 mandoc does not have these restrictions.
+.It
+Newer groff and mandoc print
+.Qq AT&T UNIX
+prior to unknown arguments of
+.Sx \&At ;
+older groff did nothing.
 .El
 .Sh SEE ALSO
 .Xr mandoc 1 ,