<!DOCTYPE book [ <!ELEMENT book (doc*)> <!ELEMENT doc (isid*)> <!ELEMENT isid EMPTY> <!ATTLIST isid myid ID #IMPLIED> ]> <book> <doc> <isid myid=“mine”/> <isid myid=“dup”/> </doc> <!– including another XML document with IDs –> <xinclude:include xmlns:xinclude=“www.w3.org/2001/XInclude”
href="../ents/ids.xml"/>
</book>