<!DOCTYPE root [
    <!ELEMENT root ANY>
    <!ATTLIST root
	id	ID	#IMPLIED
	idref	IDREF	#IMPLIED
	idrefs	IDREFS	#IMPLIED
	>
]>

<!-- each name must match the value of an id attribute on some element -->

<root idrefs="d36 ee38">
    <root id="d36"/>
</root>