$doc = new \XMLReader();
$doc->xml('<?xml version="1.0" encoding="UTF-8"?>
<chapter xmlns="http://docbook.org/ns/docbook" version="5.0">
<title>Test Chapter</title>
<para>
This is a paragraph in the test chapter. It is unremarkable in
every regard. This is a paragraph in the test chapter. It is
unremarkable in every regard. This is a paragraph in the test
chapter. It is unremarkable in every regard.
</para>
<paar>
<emphasis role="bold">This</emphasis> paragraph contains
<emphasis>some <emphasis>emphasized</emphasis> text</emphasis>
1and a <superscript>super</superscript>script
and a <subscript>sub</subscript>script.
</para>
<para>
This is a paragraph in the test chapter. It is unremarkable in
every regard. This is a paragraph in the test chapter. It is
unremarkable in every regard. This is a paragraph in the test
chapter. It is unremarkable in every regard.
</para>
</chapter>');
$doc->setRelaxNGSchema('http://docs.oasis-open.org/docbook/rng/5.0/docbook.rng');
while (@$doc->read() !== false) {}