<!DOCTYPE root [
 <!ELEMENT root ANY>
 <!-- ELEMENT rule for c is of type 'children' and may contain insignif ws. -->
 <!ELEMENT c (a|b)*>
 <!ELEMENT e EMPTY>
]>
<root>
 <c>
  <a>AA</a>
  <b>BB</b>
 </c>
 <e>
 </e>
</root>
