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>
    <allimages gaicontinue="CH1_TRI1_3.png" />
  </query-continue>
  <query>
    <pages>
      <page pageid="43" ns="6" title="File:CH1 Map1.png" />
      <page pageid="113" ns="6" title="File:CH1 Map2.png" />
      <page pageid="114" ns="6" title="File:CH1 Map3.png" />
      <page pageid="115" ns="6" title="File:CH1 Map4.png" />
      <page pageid="116" ns="6" title="File:CH1 Map5.png" />
      <page pageid="117" ns="6" title="File:CH1 Map6.png" />
      <page pageid="20" ns="6" title="File:CH1 Preview.png" />
      <page pageid="27" ns="6" title="File:CH1 TR1 1.png">
        <duplicatefiles>
          <df name="CH1_TRI1_1.png" user="Runouw" timestamp="2015-05-15T19:00:47Z" />
        </duplicatefiles>
      </page>
      <page pageid="30" ns="6" title="File:CH1 TRI1 1.png">
        <duplicatefiles>
          <df name="CH1_TR1_1.png" user="Runouw" timestamp="2015-05-15T18:53:59Z" />
        </duplicatefiles>
      </page>
      <page pageid="44" ns="6" title="File:CH1 TRI1 2.png" />
    </pages>
  </query>
</api>