<?xml version="1.0"?><!DOCTYPE book [
<!ELEMENT book (doc)*><!ELEMENT doc (isid)*><!ELEMENT isidEMPTY><!ATTLIST isidmyidID#IMPLIED>
]><book><doc><isidmyid="mine"/><isidmyid="dup"/></doc><!-- including another XML document with IDs --><docxml:base="../ents/ids.xml"><isidmyid="dup"/><isidmyid="foo"/><isidmyid="bar"/></doc></book>