(PHP 5, PHP 7)
DOMElement::setIdAttributeNode — Declares the attribute specified by node to be of type ID
   Declares the attribute specified by attr to be of
   type ID.
  
attrThe attribute node.
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.