public delegate void UnreferencedObjectEventHandler( object sender, UnreferencedObjectEventArgs e);

This declared delegate type is used to receive event notifications from an XmlSerializer instance of unreferenced objects in the XML data stream. An unreferenced object is an element that occurs in a SOAP envelope but whose id attribute is not referenced by any other element's href attribute. When this callback is invoked, you have the opportunity to examine the unreferenced object through the UnreferencedObjectEventArgs.