diff --git a/reference/array/functions/usort.xml b/reference/array/functions/usort.xml
index 0c4773d29f..b0efcaf324 100644
--- a/reference/array/functions/usort.xml
+++ b/reference/array/functions/usort.xml
@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="iso-8859-1"?>
-<!-- $Revision: 1.4 $ -->
+<!-- $Revision: 1.5 $ -->
 <!-- splitted from ./en/functions/array.xml, last change in rev 1.2 -->
   <refentry id="function.usort">
    <refnamediv>
@@ -25,8 +25,15 @@
      The comparison function must return an integer less than, equal
      to, or greater than zero if the first argument is considered to
      be respectively less than, equal to, or greater than the
-     second. If two members compare as equal, their order in the
-     sorted array is undefined.
+     second. 
+     <note>
+      <para>
+       If two members compare as equal, their order in the sorted array is undefined.
+       Up to PHP 4.0.6 the user defined functions would keep the original order for
+       thoes elements, but with the new sort algorithm intruduced with 4.1.0 this
+       is no longer the case as there is no solution to do so in an efficient way.
+      </para>
+     </note>
     </para>
     <para>
      <example>