- var_dump: documentation ( source)
- preg_replace: documentation ( source)
<?php
$xmlFile = "<ss:Data ss:Type=\"String\"
xmlns=\"http://www.w3.org/TR/REC-html40\">";
$xmlFile = preg_replace('/ss:Data ss:Type="String"(\s|.)+>/', 'ss:Data ss:Type="String', $xmlFile);
var_dump($xmlFile);