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HTML is good for debugging, but is unsuitable for application use.
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To see the non HTML representation of the XML format, set format=xml.
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<?xml version="1.0"?>
<api>
  <query-continue>
    <allcategories accontinue="三重県" />
  </query-continue>
  <query>
    <allcategories>
      <c size="0" pages="0" files="0" subcats="0" xml:space="preserve">Memo</c>
      <c size="92" pages="92" files="0" subcats="0" xml:space="preserve">『おもろさうし』の地名</c>
      <c size="2159" pages="2159" files="0" subcats="0" xml:space="preserve">『和名類聚抄』の郷名</c>
      <c size="0" pages="0" files="0" subcats="0" xml:space="preserve">『和名類聚抄』の郷名からみつける</c>
      <c size="0" pages="0" files="0" subcats="0" xml:space="preserve">【県名】</c>
      <c size="18" pages="18" files="0" subcats="0" xml:space="preserve">【福岡県】</c>
      <c size="0" pages="0" files="0" subcats="0" xml:space="preserve">アイヌ語の地名</c>
      <c size="622" pages="622" files="0" subcats="0" xml:space="preserve">アイヌ語の地名(北海道)</c>
      <c size="174" pages="174" files="0" subcats="0" xml:space="preserve">アイヌ語の地名(東北)</c>
      <c size="115" pages="115" files="0" subcats="0" xml:space="preserve">一般提供情報</c>
    </allcategories>
  </query>
</api>