diff --git a/reference/spl/parentiterator.xml b/reference/spl/parentiterator.xml
index a7d34f9318..a673377f3d 100644
--- a/reference/spl/parentiterator.xml
+++ b/reference/spl/parentiterator.xml
@@ -10,7 +10,9 @@
   <section xml:id="parentiterator.intro">
    &reftitle.intro;
    <para>
-    
+    This extended <classname>FilterIterator</classname> allows a recursive
+    iteration using <classname>RecursiveIteratorIterator</classname> that only
+    shows those elements which have children.
    </para>
   </section>
 <!-- }}} -->