diff --git a/reference/yaf/appconfig.xml b/reference/yaf/appconfig.xml
index 33b9b61d9d..a986ec8101 100644
--- a/reference/yaf/appconfig.xml
+++ b/reference/yaf/appconfig.xml
@@ -232,7 +232,9 @@ yaf.dispatcher.catchException = 0
      </term>
      <listitem>
       <para>
-       Introduced in Yaf 2.1.6
+       Alias of <link
+        linkend="configuration.yaf.library">application.library</link>. Introduced
+       in Yaf 2.1.6
       </para>
      </listitem>
     </varlistentry>
diff --git a/reference/yaf/yaf_loader/registerlocalnamespace.xml b/reference/yaf/yaf_loader/registerlocalnamespace.xml
index 5d0a83d914..601430c31c 100644
--- a/reference/yaf/yaf_loader/registerlocalnamespace.xml
+++ b/reference/yaf/yaf_loader/registerlocalnamespace.xml
@@ -11,10 +11,34 @@
   &reftitle.description;
   <methodsynopsis>
    <modifier>public</modifier> <type>void</type><methodname>Yaf_Loader::registerLocalNamespace</methodname>
-   <methodparam choice="opt"><type>mixed</type><parameter>prefix</parameter></methodparam>
+   <methodparam><type>mixed</type><parameter>prefix</parameter></methodparam>
   </methodsynopsis>
   <para>
-   register local class prefix
+   Register local class prefix name, <classname>Yaf_Loader</classname> search
+   classes in two library directories, the one is configured via <link
+    linkend="configuration.yaf.library">application.library.directory</link>(in
+   application.ini) which is called local libraray directory; the other is
+   configured via <link linkend="ini.yaf.library">yaf.library</link> (in
+   php.ini) which is callled global library directory, since it can be shared
+   by many applications in the same server. 
+  </para>
+  <para>
+   When an autloading is trigger, <classname>Yaf_Loader</classname> will
+   determine which library directory should be searched in by exame the prefix
+   name of the missed classname.
+
+   If the prefix name is registered as a localnamespack then look for it in
+   local library directory, otherwise look for it in global library directory.
+   <note>
+    <para>
+     If yaf.library is not configured, then the global library directory is
+     assumed to be the local library directory. in that case, all autoloading
+     will look for local library directory. 
+
+     But if you want your Yaf application be strong, then always register your
+     own classes as local classes.
+    </para>
+   </note>
   </para>
  </refsect1>