<?xml version="1.0"?>
<!DOCTYPE root SYSTEM "ibm50v01.dtd" [
  <!ELEMENT root (a,b)>
]>
<root><a/><b>
   <c><child1><a/><b></b><c></c></child1></c >
   <c><child2><a/><b></b><c></c></child2></c >
   content of b element
</b></root>
<!--* a valid test: tests VC:Proper Group/PE Nesting in P50 *-->
