<?xml version='1.0' ?>
<!DOCTYPE test  [
<!ELEMENT test (#PCDATA|inner)* >
<!ELEMENT inner (#PCDATA) >
<!ATTLIST inner attr CDATA #IMPLIED >
<!ENTITY t1 "t2=&t2;...">
<!ENTITY t2 "t3=&t3;...">
<!ENTITY t3 "t1=&t1;...">
]>
<!-- Recursive entity substitution in attribute -->
<test>
  <inner attr="Attr text &t2;." />
</test>