You can validate a XML file against a DTD using
isValid() like in the example below:
<?php
require_once 'XML/DTD/XmlValidator.php';
$dtd_file = realpath('myfile.dtd');
$xml_file = realpath('myfile.xml');
$validator = new XML_DTD_XmlValidator();
if (!$validator->isValid($dtd_file, $xml_file)) {
die($validator->getMessage());
}
?>
isValid() will return true when the XML
document validates and false otherwise.
This is pretty much the most common usage of XML_DTD and all you need to know to get started.