(PHP 5, PHP 7)
DOMElement::setIdAttributeNS — Declares the attribute specified by local name and namespace URI to be of type ID
$namespaceURI
   , string $localName
   , bool $isId
   )
   Declares the attribute specified by localName and 
   namespaceURI to be of type ID.
  
namespaceURIThe namespace URI of the attribute.
localNameThe local name of the attribute, as prefix:tagname.
isId
       Set it to TRUE if you want name to be of type
       ID, FALSE otherwise.
      
No value is returned.
DOM_NO_MODIFICATION_ALLOWED_ERRRaised if the node is readonly.
DOM_NOT_FOUND
       Raised if name is not an attribute of this element.