1  <!DOCTYPE book [
 2  <!ELEMENT book (doc*)>
 3  <!ELEMENT doc (isid*)>
 4  <!ELEMENT isid EMPTY>
 5  <!ATTLIST isid myid ID #IMPLIED>
 6  ]>
 7  <book>
 8  <doc>
 9  <isid myid="mine"/>
10  <isid myid="dup"/>
11  </doc>
12  <!-- including another XML document with IDs -->
13  <xinclude:include xmlns:xinclude="http://www.w3.org/2001/XInclude"
14  		 href="../ents/ids.xml"/>
15  </book>