Under the FDA's Food Traceability Rule, critical tracking events are the moments in a food's journey where records must be kept: harvesting, cooling, initial packing, first land-based receiving (for seafood), shipping, receiving and transformation.
Most distributors are concerned mainly with receiving and shipping, and with transformation if they repack, cut or otherwise change a product. Each event has its own list of key data elements to record. Recording them as the work happens is far easier than rebuilding them from paper after a request.
In APFoodz a lot's tracking events are recorded as the work happens.
Source: FDA: Food Traceability Rule