root/ext/xmlreader/examples/xmlreader_validatedtd.php

<?php
$indent = 5; /* Number of spaces to indent per level */

$xml = new XMLReader();
$xml->open("dtdexample.xml");
$xml->setParserProperty(XMLREADER::LOADDTD, TRUE);
$xml->setParserProperty(XMLREADER::VALIDATE, TRUE);
while($xml->read()) {
        /* Print node name indenting it based on depth and $indent var */
        print str_repeat(" ", $xml->depth * $indent).$xml->name."\n";
        if ($xml->hasAttributes) {
                $attCount = $xml->attributeCount;
                print str_repeat(" ", $xml->depth * $indent)." Number of Attributes: ".$xml->attributeCount."\n";
        }
}
print "\n\nValid:\n";
var_dump($xml->isValid());