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>
    <alllinks>
      <l fromid="1" ns="0" title="Byrd Polar and Climate Change Research Center, The Ohio State University" />
      <l fromid="4" ns="0" title="Fa-cogs" />
      <l fromid="1" ns="0" title="Lamont-Doherty Core Repository Sediment Cores and Dredges" />
      <l fromid="1" ns="0" title="Lamont-Doherty Earth Observatory" />
      <l fromid="1" ns="0" title="Polar Rock Repository" />
    </alllinks>
  </query>
</api>