 unmarshal,
   validate, and marshal operations:
    <dl>
        <dt>Use the default event handler</dt>
        <dd>The default event handler will be used if you do not specify one
            via the <code>setEventHandler</code> API's on <code>Validator</code>,
            <code>Unmarshaller</code>, or <code>Marshaller</code>.
        </dd>
 
        <dt>Implement and register a custom event handler</dt>
        <dd>Client applications that require sophisticated event processing
            can implement 