1<!DOCTYPE root [
2  <!ATTLIST x id ID #IMPLIED>
3]>
4<root xmlns:xi="http://www.w3.org/2001/XInclude" xml:base="http://www.example.org/">
5<xi:include href="" xpointer="foo"/>
6<x id="foo">
7  <xi:include href="" xpointer="bar"/>
8</x>
9<x id="bar"/>
10</root>