diff --git a/docs/PortKnocking.xml b/docs/PortKnocking.xml
index f26b5bdb5..af3793cdb 100644
--- a/docs/PortKnocking.xml
+++ b/docs/PortKnocking.xml
@@ -15,11 +15,13 @@
       </author>
     </authorgroup>
 
-    <pubdate>2005-12-06</pubdate>
+    <pubdate>2006-03-15</pubdate>
 
     <copyright>
       <year>2005</year>
 
+      <year>2006</year>
+
       <holder>Thomas M. Eastep</holder>
     </copyright>
 
@@ -193,6 +195,13 @@ SSHLimit         net               loc:192.168.1.5 tcp         22            -
     <para id="Limit">The above can be generalized into a flexible 'Limit'
     target.</para>
 
+    <note>
+      <para>'Limit' as described here is included as a standard part of
+      Shorewall beginning with version 3.0.4. The following is included to
+      show how 'Limit' is implemented; if you are running Shorewall 3.0.4 or
+      later, you can omit the following two steps.</para>
+    </note>
+
     <orderedlist>
       <listitem>
         <para>Add an action named Limit. Leave the action.Limit file