Every new address or new update to an existing address causes a new CAF ID to be created, which will be higher than any other CAF ID already in the database. Hence the highest CAF ID acts as a version number for the CAF database as a whole.
The GetUpdates call provides systems with a means of receiving notification about all new updates in CAF. It is recommended that client systems call GetUpdates nightly, passing in the highest CAF ID which the client system is aware of, and take appropriate action for each of the Updates returned. The CAF ID returned in the UpdateList object should be stored in order to be passed back when calling GetUpdates again the following night.
For more information about suggested ways of processing an update, see the Update documentations.