1  <?xml version="1.0"?>
 2  <!DOCTYPE root [
 3  <!ENTITY % deftest "&#60;!ELEMENT test (#PCDATA) >">
 4  <!ENTITY % defmiddle "&#60;!ELEMENT middle (test) >">
 5  <!ENTITY % defroot "&#60;!ELEMENT root (middle) >">
 6  <!ELEMENT root (middle)>
 7  <!ELEMENT middle (test)>
 8  <!ELEMENT test (#PCDATA)>
 9  ]>
10  <root><middle><test>sample</test></middle></root>