<?xml version="1.0"?>
<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN" "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd" [
  <!ENTITY tex "TeX">
  <!ENTITY latex "LaTeX">
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<book id="extension_undef" lang="en">
<chapter label="">
<title>top</title>

</chapter>
<chapter label="1" id="chapter">
<title>Chap</title>
</chapter>
</book>
