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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.
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<?xml version="1.0"?>
<api>
  <query-continue>
    <allfileusages gafcontinue="Figure_1.2_-_Antarctic_topography_and_bathymetry.png|278" />
  </query-continue>
  <query>
    <pages>
      <page pageid="241" ns="0" title="Marine biota of the Antarctic" />
      <page pageid="278" ns="0" title="The Antarctic cryosphere" />
      <page pageid="283" ns="0" title="The climate of the Antarctic and its variability" />
      <page pageid="293" ns="0" title="The physical setting of Antarctica" />
      <page pageid="294" ns="0" title="The role of the Antarctic in the global climate system" />
    </pages>
  </query>
</api>