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>
    <allpages apcontinue="Changing_Image_Contrast" />
  </query-continue>
  <query>
    <allpages>
      <p pageid="321" ns="0" title="B-Spline Automatic Registration" />
      <p pageid="322" ns="0" title="B-Spline Automatic Registration Dialog box" />
      <p pageid="323" ns="0" title="BSpline registration: Detecting folding" />
      <p pageid="324" ns="0" title="Background" />
      <p pageid="325" ns="0" title="Barrel Distortion Correction" />
      <p pageid="326" ns="0" title="Browsing DICOM images" />
      <p pageid="327" ns="0" title="Building and compiling plug-in programs" />
      <p pageid="328" ns="0" title="Calculating VOI statistics" />
      <p pageid="329" ns="0" title="Calculating statistics on VOI groups" />
      <p pageid="330" ns="0" title="Calculating the volume of masks" />
    </allpages>
  </query>
</api>