C2MS12 — Split ME1 in Simple Service Req/Resp

Simple Service Request uses ME1 to indicate the target of the request, but this can have one of two mutually-exclusive forms:

• Service Provider Name (a named instance of a component, such as FDServiceApp1)
• A Service Name not related to a specific component (such as Flight Dynamics)

Meanwhile, the Simple Service Response also uses ME1 in a similar, but slightly different way. In the RESP, ME1 represents one of two mutually exclusive forms:

• A Requestor Name (a named instance of a components that requested a service, or will receive data from the Service Provider, such as C2App7)
• A Service Name not specific to a component (such as Flight Dynamics)

Note that when using ME1 to designate a component, it is always the target recipient of the request/response, but when specifying a Service Name, it is always the name of the Service Provided, which is more related to the responder than the requestor. In this way, the Request Message uses that form of ME1 to designate the recipient, but the Response Message in that form designates to the provider.

This dual-hatting of ME1 is pretty confusing. One major user of C2MS has modified these messages to separate out the two uses of ME1 into ME1 and ME2, shifting ME2 and ME3 to the right.

This issue reqeusts to do that same thing, matching the modification made by that major user.