<?xml version="1.0" encoding="UTF-8"?>
<book xmlns="http://docbook.org/ns/docbook" version="5.0">
    <info>
        <title>Invalid DocBook Document</title>
    </info>
    <chapter>
        <title>Test Chapter</title>
        <para>This paragraph is valid.</para>
        <para unknown="">This paragraph has an invalid attribute.</para>
    </chapter>
</book>
