<?xml version="1.0"?>
<!DOCTYPE root [
  <!ELEMENT root (a,b)>
  <!ELEMENT a EMPTY>
  <!ELEMENT b (#PCDATA|c)* >
  <!ELEMENT c ANY>
  <!ELEMENT f EMPTY>
]>
<!--* element c has undeclared element as its ANY content *-->
<root><a/><b>
   <c><f/></c> 
   content of b element
   <c>
      <d>not declared in dtd</d>
   </c>
</b></root>