Only identified baggage can be sorted. System wide tracking is one way to identify items entering the sorter. For items to be identified, items must be registered. Registered items can then be tracked, compared, and identified. Registration, tracking, comparison, and validation, all contribute to the volume of network information that slows system performance.
Baggage can enter the system freely, but it enters into flowing traffic.
An entering item must wait for clearance to avoid collision. A system of traffic control is required for the entering items. A small buffer is necessary to hold items waiting for clearance. In batch processing sytem, baggage enters the system in batches. System scheduler determines the state of the gates.