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="BBC_Sessions_(Led_Zeppelin_album)|736" />
  </query-continue>
  <query>
    <pages>
      <page pageid="393" ns="10" title="Template:Navbox musical artist" />
      <page pageid="398" ns="10" title="Template:Below columns" />
      <page pageid="744" ns="10" title="Template:Wikipedia&#039;s sister projects" />
      <page pageid="758" ns="10" title="Template:Tag" />
      <page pageid="859" ns="10" title="Template:Tag/doc" />
      <page pageid="1140" ns="0" title="SYSREL INFRASTRUCTURE" />
      <page pageid="1543" ns="0" title="SYSREL DOCUMENT" />
      <page pageid="1546" ns="0" title="SYSREL RULE" />
      <page pageid="1552" ns="0" title="SYSREL VIEWROOT" />
      <page pageid="2187" ns="0" title="List of MetaClasses" />
    </pages>
  </query>
</api>