All key processing in N4 is followed by the issuance of an Event. An Event signals a particular transaction has occurred to a domain entity (unit, booking, etc.). Each Event is categorized by its Event Type such as "Discharge Container from Vessel", "Deliver Container to Truck", etc. In addition to such built-in Event Types, Users can extend N4 by defining their own Event Types.
Through the Notices UI, a user can configure actions that should be taken upon the occurrence of an Event. In the initial releases of N4 these actions were limited to issuance of email and printing of documents. Users can control the circumstances under which the configured actions are taken based on an arbitrary Filter. All of this is covered in the on-line documentation, so we won't belabor it further here.