The DOMImplementation interface provides a number of methods for performing operations that are independent of any particular instance of the document object model.
officially, the w3 specifies that the way to access dom interfaces is through this class
so if you use
$doc = new DOMDocument("1.0", "UTF-8");
use instead:
$x = new DOMImplementation();
$doc = $x->createDocument(NULL,"rootElementName");
$doc->xmlVersion="1.0";
$doc->xmlEncoding="UTF-8";
it is not required by php's implementation, but, probably, it is a good practice
see:
http://w3.org/TR/DOM-Level-3-Core/core.html#DOMImplementation
http://w3.org/TR/DOM-Level-3-Core/core.html#DOMImplementationList
http://w3.org/TR/DOM-Level-3-Core/core.html#DOMImplementationSource