diff --git a/functions/dir.xml b/functions/dir.xml
index 643b2ee350..41ff172c39 100644
--- a/functions/dir.xml
+++ b/functions/dir.xml
@@ -1,9 +1,20 @@
 <?xml encoding="iso-8859-1"?>
-<!-- $Revision: 1.21 $ -->
+<!-- $Revision: 1.22 $ -->
  <reference id="ref.dir">
   <title>Directory functions</title>
   <titleabbrev>Directories</titleabbrev>
 
+  <partintro>
+  
+   <simpara>
+    For related functions such as <function>dirname</function>,  
+    <function>is_dir</function>, <function>mkdir</function>, and 
+    <function>rmdir</function>, see the 
+    <link linkend="ref.filesystem">Filesystem</link> section.
+   </simpara>
+  
+  </partintro>
+  
   <refentry id="function.chroot">
    <refnamediv>
     <refname>chroot</refname>