some of our specs (enum, eventing) define new EPRs that are to be used for
server initiated message exchanges.  While its implied that those messages
should be sent using the same version of SOAP that was used to carry the
original EPR, it should be more explicit to avoid interop issues.

Proposal:
In the definition of EndTo (eventing, enum) and NotifyTo (eventing), add:

Unless some mechanism is used to indicate otherwise, the messages sent to 
this endpoint MUST use the same version of SOAP that was used for the (Subscribe|Enumerate) message.