When an alert is received in BES, it is categorised as either 'New' or 'Changed'. The definitions are as follows:
New = An alert at the instance it is created inside AlertServer.
Changed = Any alert updated by an update field <UF> event.
A change is only registered via an UpdateField event which excludes a recurrence which has a different event type in it's own right. UpdateField events are any event that physically changes a property of the alert e.g. a CAF Field, the Severity, Timeout etc.