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>
    <allpages>
      <p pageid="201" ns="0" title="Background data import" />
      <p pageid="205" ns="0" title="Calculation parameters definition" />
      <p pageid="35" ns="0" title="Change Log Kalypso 10.10.0" />
      <p pageid="66" ns="0" title="Change Log Kalypso 11.6.0" />
      <p pageid="144" ns="0" title="Change Log Kalypso 11.6.1" />
      <p pageid="155" ns="0" title="Change Log Kalypso 11.6.2" />
      <p pageid="156" ns="0" title="Change Log Kalypso 12.11" />
      <p pageid="256" ns="0" title="Change Log Kalypso 12.11.1" />
      <p pageid="251" ns="0" title="Change Log Kalypso 12.7.0" />
      <p pageid="272" ns="0" title="Change Log Kalypso 13.12" />
    </allpages>
  </query>
  <query-continue>
    <allpages apcontinue="Change_Log_Kalypso_13.x" />
  </query-continue>
</api>