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>
    <alllinks galcontinue="PXV:AFS_FileIoModeFlags" />
  </query-continue>
  <query>
    <pages>
      <page pageid="25" ns="0" title="IndexTypeLibrary" />
      <page pageid="4815" ns="0" title="PXV:AFS" />
      <page pageid="2" ns="0" title="PXV:AFS BindContextFlags" />
      <page pageid="4" ns="0" title="PXV:AFS BindFlags" />
      <page pageid="4364" ns="0" title="PXV:AFS CloseFileFlags" />
      <page pageid="5" ns="0" title="PXV:AFS DlgFlags" />
      <page pageid="6" ns="0" title="PXV:AFS DlgTypes" />
      <page pageid="5159" ns="0" title="PXV:AFS Enumerations" />
      <page pageid="4365" ns="0" title="PXV:AFS FeaturesFlags" />
      <page pageid="7" ns="0" title="PXV:AFS FileAttributes" />
    </pages>
  </query>
</api>