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="CifXDrv_devmgmt_netPLC_01de.PNG|820" />
  </query-continue>
  <query>
    <pages>
      <page pageid="8" ns="0" title="Dokumentation S5/S7 für Windows" />
      <page pageid="75" ns="0" title="S5/S7 für Windows:Statusrecorder" />
      <page pageid="589" ns="0" title="IBHNet:Betrieb mit WinCC Flexible" />
      <page pageid="793" ns="0" title="IBHLink S7++:SPS-SPS Kommunikation" />
      <page pageid="975" ns="0" title="IBH USB-S5-Adapter:SIMATIC® S5 S5 für Windows®" />
      <page pageid="986" ns="0" title="S7-SoftSPS:Konfiguration der CIF-Karte mit dem Systemkonfigurator" />
      <page pageid="1068" ns="0" title="S5/S7 für Windows:Bausteine aus SPS Backup Archiven auslesen" />
    </pages>
  </query>
</api>