3.2.6.2 Server or List Restoration

If a protocol server restores data from backups then protocol clients might not be able to determine the correct state of the items. Protocol clients SHOULD discard their local data because the protocol server might have been restored to undo changes that protocol clients still have. Protocol clients can keep a backup of changes that were not uploaded to the protocol server. A protocol server or list restoration event is indicated by Changes.Id.ChangeType="restore" and no data in the Changes.Id listed in section 3.1.4.7.1.1.