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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.
See the complete documentation, or API help for more information. 
<?xml version="1.0"?>
<api>
  <query-continue>
    <allfileusages afcontinue="Figure_1.3_-_Antarctic_surface_elevation.png" />
  </query-continue>
  <query>
    <allfileusages>
      <f ns="6" title="File:Figure 1.10 - Major currents south of 20S.png" />
      <f ns="6" title="File:Figure 1.11 - Column inventories of anthropogenic CO2 in the ocean.png" />
      <f ns="6" title="File:Figure 1.12 - Schematic of the biological and physical pump.png" />
      <f ns="6" title="File:Figure 1.13 - The Antarctic polar vortex in mid-winter.png" />
      <f ns="6" title="File:Figure 1.14 - Percentage of Antarctic macrobenthic invertebrate species of the described world fauna.png" />
      <f ns="6" title="File:Figure 1.15 - A rich megabenthic community on the shelf of the southeastern Weddell Sea.png" />
      <f ns="6" title="File:Figure 1.16 - Classification of macro-benthic communities on the continental Antarctic shelf.png" />
      <f ns="6" title="File:Figure 1.1a - Map of Antarctica.png" />
      <f ns="6" title="File:Figure 1.1b - Map of Antarctic stations.png" />
      <f ns="6" title="File:Figure 1.2 - Antarctic topography and bathymetry.png" />
    </allfileusages>
  </query>
</api>