<?xml version='1.0'?> <!DOCTYPE root [ <!ENTITY % deftest '&#60;!ELEMENT test (#PCDATA) >' > <!ENTITY % defmiddle '&#60;!ELEMENT middle (test) >' > <!ENTITY % defroot '&#60;!ELEMENT root (middle) >' > %defroot; %defmiddle; %deftest; ]> <root><middle><test>sample</test></middle></root>