PMode[2].BusinessInfo.Action

Suppose you have a Two Way MEP with request action "SubmitOrder" and a response action "AcceptOder.

In the PMode syntax this could be written as:

PMode[1].BusinessInfo.Action = "SubmitOrder"
PMode[2].BusinessInfo.Action= "AcceptOder"

But if there are two, mutually exclusive response actions "AcceptOrder" and "RejectOrder", what is the notation to use? Or is this not supported?
This is a common pattern in many e-business applications.