<?xml version="1.0"?>
<!DOCTYPE root [
  <!ELEMENT root ANY>
  <!ELEMENT a (#PCDATA)* >
  <!ELEMENT b (#PCDATA) >
  <!ELEMENT c ( #PCDATA)*>
  <!ELEMENT d (#PCDATA|c)* >
  <!--* Duplicate element types in Mixed content decl *-->
  <!ELEMENT e (#PCDATA|a|a|b|c)* >
]>
<root>
  <a> Element type a </a>
  <b> Element type b </b>
</root>
<!--* a invalid test: tests P51 VC: No Duplicate Types *-->
