proposal for issue 8832

Attached is a proposal for issue 8832. As suggested on a recent call, 
this proposal copies one of the recent changes to WS-Enumeration by 
adding the following text to section 4:

A subscription can become invalid for any reason including:

   1. Subscription deleted (via Unsubscribe)
   2. Subscription expired
   3. Subscription ended (via SubscriptionEnd)

In addition, the Event Source/Subscription Manager MAY cancel a 
subscription at any time, as necessary.

When processing a Renew, GetStatus or Unsubscribe operation, a 
Subscription Manager MUST generate an wse:UnknownSubscription fault if 
it determines that the subscription is invalid. Once a Subscriber 
determines that a subscription is invalid, it MUST NOT issue any more 
WS-Eventing request messages using that subscription.

I've attached an edited HTML version along with a PDF that highlights 
the changes.

- gp