A port is where the vessel berths, but it is also the dividing point between land and sea. In exports, cargo enters through the gate, is checked, is stacked in the yard and is lifted aboard by crane when the vessel berths. In imports it works the other way round: cargo is discharged from the vessel, waits in the yard and is handed to a truck once customs and document formalities are done.
The logic here is simple but strict: each step depends on the one before it being completed. Without an appointment the truck waits at the gate, with a document missing the cargo does not enter the yard, and if an inspection is called the delivery slips. Every extra hour spent in port can turn into a cost item.