diff --git a/functions/strings.xml b/functions/strings.xml
index c05d88bf5d..5db6b0d915 100644
--- a/functions/strings.xml
+++ b/functions/strings.xml
@@ -1915,6 +1915,48 @@ soundex ("Lukasiewicz") == soundex ("Lissajous") == 'L222';
       </listitem>
      </orderedlist>
     </para>
+	<para>
+	As of PHP version 4.0.6 the format string supports argument
+    numbering/swapping.  Here is an example:
+	<example>
+	 <title>Argument swapping</title>
+	 <programlisting role="php">
+$format = "There are %d monkeys in the %s";
+printf($format,$num,$location);
+	 </programlisting>
+	</example>
+	This might output, "There are 5 monkeys in the tree".  But imagine we are
+	creating a format string in a separate file, commonly because we would like to
+	internationalize it and we rewrite it as:
+	<example>
+	 <title>Argument swapping</title>
+	 <programlisting role="php">
+$format = "The %s contains %d monkeys";
+printf($format,$num,$location);
+	 </programlisting>
+	</example>
+	We now have a problem.  The order of the placeholders in the format string
+	does not match the order of the arguments in the code.  We would like to
+	leave the code as is and simply indicate in the format string which arguments
+	the placeholders refer to.  We would write the format string like this
+	instead:
+	<example>
+	 <title>Argument swapping</title>
+	 <programlisting role="php">
+$format = "The %2\$s contains %1\$d monkeys";
+printf($format,$num,$location);
+	 </programlisting>
+	</example>
+	An added benefit here is that you can repeat the placeholders without
+	adding more arguments in the code.  For example:
+	<example>
+	 <title>Argument swapping</title>
+	 <programlisting role="php">
+$format = "The %2\$s contains %1\$d monkeys.  That's a nice %2\$s full of %1\$d monkeys.";
+printf($format,$num,$location);
+	 </programlisting>
+	</example>
+	</para>
     <simpara>
      See also: <function>printf</function>, <function>sscanf</function>,
 	 <function>fscanf</function>, and <function>number_format</function>.