[ebxml-msg] Issue 41: Acknowledgment/RefToMessageId element

This issue points to a fundamental and inconsistent change in the 2.0
specification when compared with the 1.0 version.  We have previously agreed
and documented in numerous locations that ebMS signals referencing a
particular incoming message must be sent in a message that uses the
MessageHeader/RefToMessageId element appropriately.

David has suggested this addition (which was not discussed by the group since
I rejoined) supports bundling acknowledgements.  What makes acknowledgements
special in this regard?  What about errors, responses to multiple message
status requests, et cetera?

I recommend we remove this element, especially because it is required and
would normally just duplicate the value appearing in
MessageHeader/RefToMessageId.

thanx,
    doug