Why does XDS use External Classifications for document coding?
Both Internal and External Classification systems are available in ebXML Registry. In XDS the use of Internal Classifications was avoided for document coding. When a Classification object is returned that references an Internal Classification, the user must another query to the registry to look-up the names of the classification referenced so that a results listing can be produced. With an External Classification, the coded value is returned in the Classification object in the original query result. Since we expect XDSRegistry servers to handle a very large load and individual listing displays will likely contain many documents, we made several design choices to minimize the number of requests to the XDSRegistry server required to produce a listing display.
