Part of the mechanism for eBay to control which announcement messages are to be made available to the user.
No message is to be made available.
A deprecation message is to be made available, but only if today's date is between AnnouncementMessageType.AnnouncementStartTime and AnnouncementMessageType.EventTime.
A mapping message is to be made available, but only if today's date is after AnnouncementMessageType.EventTime.
Both "Deprecation" and "Mapping" enumerations are to apply.
Reserved for future use.