Untitled

<?php

$html = <<<EOF
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
  <head>
  </head>
  <body>
    <p>&nbsp;</p>
  </body>
</html>
EOF;

// This one works perfectly.
$dom = new DOMDocument();
$dom->loadXML($html, LIBXML_DTDLOAD);

//Do here what you will.

print $dom->saveXML();

?>