Code example for DTDHandler
public void unparsedEntityDecl(String a, String b, String c, String d) throws SAXException
// ErrorHandler support.
// PROBLEM: Xerces is apparently _not_ calling the ErrorHandler for
// exceptions thrown by the ContentHandler, which prevents us from
// handling this properly when running in filtering mode with Xerces
// as our event source. It's unclear whether this is a Xerces bug
// or a SAX design flaw.
// %REVIEW% Current solution: In filtering mode, it is REQUIRED that
// event source make sure this method is invoked if the event stream
// abends before endDocument is delivered. If that means explicitly calling
// us in the exception handling code because it won't be delivered as part