<?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>