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> 16