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>
    <allcategories>
      <c size="0" pages="0" files="0" subcats="0" xml:space="preserve">1837年生</c>
      <c size="0" pages="0" files="0" subcats="0" xml:space="preserve">1904年没</c>
      <c size="2" pages="2" files="0" subcats="0" xml:space="preserve">人物</c>
      <c size="4" pages="4" files="0" subcats="0" xml:space="preserve">人物評</c>
      <c size="4" pages="4" files="0" subcats="0" xml:space="preserve">伝記</c>
      <c size="1" pages="1" files="0" subcats="0" xml:space="preserve">入地</c>
      <c size="7" pages="7" files="0" subcats="0" xml:space="preserve">兵屋</c>
      <c size="1" pages="1" files="0" subcats="0" xml:space="preserve">北海道大学</c>
      <c size="2" pages="2" files="0" subcats="0" xml:space="preserve">北海道庁</c>
      <c size="1" pages="1" files="0" subcats="0" xml:space="preserve">北海道庁長官</c>
    </allcategories>
  </query>
  <query-continue>
    <allcategories accontinue="北海道開発" />
  </query-continue>
</api>