(PHP 5, PHP 7, PHP 8)
DOMElement::setIdAttribute — Declares the attribute specified by name to be of type ID
$qualifiedName, bool $isId): void
   Declares the attribute qualifiedName to be of type ID.
  
qualifiedNameThe name of the attribute.
isId
       Set it to true if you want qualifiedName 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 qualifiedName is not an attribute of this element.