-The function \fBmenu_pattern\fR returns \fBNULL\fR on error. The function
-\fBset_menu_pattern\fR may return the following error codes:
+The function \fBmenu_pattern\fR returns a pointer, which is \fBNULL\fR if the \fImenu\fP parameter is \fBNULL\fP.
+Otherwise, it is a pointer to a string which is empty if no pattern has been set.
+It does not set errno.
+.PP
+The function \fBset_menu_pattern\fR may return the following error codes: