diff --git a/reference/array/functions/uksort.xml b/reference/array/functions/uksort.xml
index 1f7d3fad7f..a7f36b09ef 100644
--- a/reference/array/functions/uksort.xml
+++ b/reference/array/functions/uksort.xml
@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="iso-8859-1"?>
-<!-- $Revision: 1.9 $ -->
+<!-- $Revision: 1.10 $ -->
 <!-- splitted from ./en/functions/array.xml, last change in rev 1.2 -->
   <refentry id="function.uksort">
    <refnamediv>
@@ -21,6 +21,14 @@
      needs to be sorted by some non-trivial criteria, you should use
      this function.
     </para>
+    <para>
+     Function <parameter>cmp_function</parameter> should accept two
+     parameters which will be filled by pairs of <parameter>array</parameter> keys.
+     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.
+    </para>
     <para>
      <example>
       <title><function>uksort</function> example</title>