diff --git a/reference/array/functions/extract.xml b/reference/array/functions/extract.xml
index 7342e9fbfa..2bbb37044a 100644
--- a/reference/array/functions/extract.xml
+++ b/reference/array/functions/extract.xml
@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="iso-8859-1"?>
-<!-- $Revision: 1.19 $ -->
+<!-- $Revision: 1.20 $ -->
 <!-- splitted from ./en/functions/array.xml, last change in rev 1.2 -->
   <refentry id="function.extract">
    <refnamediv>
@@ -141,7 +141,8 @@
      <constant>EXTR_PREFIX_ALL</constant>, <constant>EXTR_PREFIX_INVALID</constant> 
      or <constant>EXTR_PREFIX_IF_EXISTS</constant>. If 
      the prefixed result is not a valid variable name, it is not 
-     imported into the symbol table.
+     imported into the symbol table. Prefixes are automatically separated from
+     the array key by an underscore character.
     </para>
     <para>
      <function>extract</function> returns the number of variables