http://docs.oracle.com/cd/E17667_01/doc.50/e17669/cpt_concepts.htm#
in the Changing Presence Rules section:
5. Because Alice's updated policy does not authorize Bob
as a watcher, the presence server sends a NOTIFY request to Bob's
client, notifying him that his subscription is terminated. In the NOTIFY
request, the Subscription-State header specifies terminated and the
reason is set to probation. This ends Bob's subscription with the
presence server and also ends the underlying SIP dialog. Bob's client
responds with a 200 OK message.
It uses **probation** as the reason for updated xcap policy.
Not sure if it is OMA standard or not or just Oracle interpretation.