<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>