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HTML is good for debugging, but is unsuitable for application use.
Specify the format parameter to change the output format.
To see the non HTML representation of the XML format, set format=xml.
See the complete documentation, or API help for more information. 
<?xml version="1.0"?>
<api>
  <query>
    <pages>
      <page ns="0" title="API" missing="" />
      <page pageid="1" ns="0" title="Main Page">
        <revisions>
          <rev user="27184" timestamp="2013-02-05T16:17:55Z" comment="" xml:space="preserve">Mission statement

&lt;ul&gt;
&lt;li&gt;To provide a forum for existing INCOSE members to network in a less formal environment;&lt;/li&gt;
&lt;li&gt;To promote and improve the practice of Systems Engineering;&lt;/li&gt;
&lt;li&gt;To foster connections with other professional bodies within the same regional area and thereby promote cross fertilisation of knowledge and experience across sectors and community disciplines; and&lt;/li&gt;
&lt;li&gt;To promote awareness of INCOSE UK and encourage membership.&lt;/li&gt;
&lt;/ul&gt;    

See how to make a [[new page]] on the mediawiki help system (http://www.mediawiki.org/wiki/Help:Links)</rev>
        </revisions>
      </page>
    </pages>
  </query>
</api>