Multiple PartyIDs in From and To

Hi,

    

    Sections 5.2.2.3 and 5.2.2.5 of EBMS3CORE state that there can be
    more than one PartyId in From and To elements and requires them to
    identify the same organization:

    

    eb:Messaging/eb:UserMessage/eb:PartyInfo/eb:From/eb:PartyId: The
      REQUIRED PartyId element occurs one or more times. If it occurs
      multiple times, each instance MUST identify the same organization.

    

    Appendix D.3.1 states that these values are taken from
    PMode.Initiator/Responder.Party.   

    

    A user message initiating an MEP instance under this P-Mode must
      have its eb:Messaging/eb:UserMessage/eb:PartyInfo/eb:From element
      contain the same PartyId elements as the PartyId elements defined
      in this parameter.

    

    One user thought this feature could be used to allow a receiving MSH
    to identify parties using multiple party ID types (e.g. GS1 GLN or
    D-U-N-S or whatever),  leaving a choice of which type to use to the
    sender without having to define a separate PMode for each case. 
    Another use case could be for hubs that handle messages on behalf of
    multiple organizations (e.g. branches of a single companies,  or
    different companies using a service provider) with diferent
    identifiers.   If we could just select one PartyId from the ones in
    the PMode,  we could have a single PMode for all organizations using
    the hub.  But it looks as if D.3.1. if requiring the same number of
    PartyIds have to be present, with the same content,  in the PMode
    definition and in the From/To headers.    And therefore,  it would
    be an error for an MSH to select just one PartyID from the ones
    defined in the PMode.  What do you think?

    

    Pim