<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook V3.1//EN">
<book><title>test book</title>
<part><title>test part I</title>
<chapter><title>first chapter in part I</title>
<para>para</para>
</chapter>
<chapter><title>second chapter in part I</title>
<para>para</para>
</chapter>
</part>
<part><title>test part II</title>
<chapter><title>first chapter in part II</title>
<para>para</para>
</chapter>
<chapter><title>second chapter in part II</title>
<para>para</para>
</chapter>
</part>
</book>