(Predicates for Strings): Add string-or-null-p.

lispref/ChangeLog

+2006-04-07  Reiner Steib  <Reiner.Steib@gmx.de>
+
+	* strings.texi (Predicates for Strings): Add string-or-null-p.
+
 2006-03-28  Kim F. Storm  <storm@cua.dk>
 
 	* processes.texi (Accepting Output): Remove obsolete (and incorrect)

lispref/strings.texi

@@ -102,6 +102,11 @@ This function returns @code{t} if @var{object} is a string, @code{nil}
 otherwise.
 @end defun
 
+@defun string-or-null-p object
+This function returns @code{t} if @var{object} is a string or nil,
+@code{nil} otherwise.
+@end defun
+
 @defun char-or-string-p object
 This function returns @code{t} if @var{object} is a string or a
 character (i.e., an integer), @code{nil} otherwise.