1  <!DOCTYPE doc [
 2  <!ELEMENT doc (src | dest)*>
 3  <!ELEMENT src EMPTY>
 4  <!ELEMENT dest EMPTY>
 5  <!ATTLIST src ref IDREF #IMPLIED>
 6  <!ATTLIST dest id ID #IMPLIED>
 7  <!ENTITY dest "<dest id='foo'/>">
 8  ]>
 9  <doc>
10    <src ref="foo"/>
11    &dest;
12    <src ref="foo"/>
13  </doc>
14