diff --git a/language/variables.xml b/language/variables.xml
index d1b995190c..ddc8f27714 100644
--- a/language/variables.xml
+++ b/language/variables.xml
@@ -851,6 +851,14 @@ I am bar.
      </para>
     </note>
 
+    <note>
+     <para>
+      Dots and spaces in variable names are converted to undescores. For
+      example <literal>&lt;input name="a.b" /&gt;</literal> becomes
+      <literal>$_REQUEST["a_b"]</literal>.
+     </para>
+    </note>
+
     <para>
      As shown, before PHP 4.2.0 the default value for <link
      linkend="ini.register-globals">register_globals</link>