You are looking at the HTML representation of the XML format.
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-continue>
    <allfileusages gafcontinue="CaseSelectionDmXObj.png" />
  </query-continue>
  <query>
    <pages>
      <page pageid="710" ns="6" title="File:COST FORSYS Overview WIKI System.png" />
      <page pageid="717" ns="6" title="File:COST FORSYS WG1 THESSALONIKI France.pdf" />
      <page pageid="714" ns="6" title="File:COST FORSYS WG1 THESSALONIKI Ireland.pdf" />
      <page pageid="711" ns="6" title="File:COST FORSYS WG1 THESSALONIKI MELA.pdf" />
      <page pageid="716" ns="6" title="File:COST FORSYS WG1 THESSALONIKI Portugal.pdf" />
      <page pageid="713" ns="6" title="File:COST FORSYS WG1 THESSALONIKI Russia.pdf" />
      <page pageid="715" ns="6" title="File:COST FORSYS WG1 THESSALONIKI SIMO.pdf" />
      <page pageid="712" ns="6" title="File:COST FORSYS WG1 THESSALONIKI Spain.pdf" />
      <page pageid="480" ns="6" title="File:Capsis415 mac.png" />
      <page pageid="481" ns="6" title="File:Capsis ventoux.png" />
    </pages>
  </query>
</api>