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_hwinst_netPLC_04en.png|296" />
  </query-continue>
  <query>
    <pages>
      <page pageid="186" ns="0" title="IBHNet:Using IBHNet with WinCC Flexible" />
      <page pageid="296" ns="0" title="S7-PCI315:Device Driver Setup" />
      <page pageid="358" ns="0" title="IBH USB-S5-Adapter:SIMATIC® S5 for Windows®" />
      <page pageid="467" ns="0" title="S7-SoftPLC:Configuring the CIF-card with the SyCon System Configurator" />
      <page pageid="536" ns="0" title="IBHLink S7++:PLC-PLC communication" />
      <page pageid="582" ns="0" title="S5/S7 for Windows:S5 COM packages" />
    </pages>
  </query>
</api>