The valid B, S or Z numbers given in ZAPP are considered as releases for loading. All shipments in the port system can be registered and receive a B-, S- or Z-number depending on the registration. For containers, carriers/agents may use the following indicators instead of the ZAPP references:
L (empty container)
An empty container, possibly also with packaging (for example, containers with empty fish boxes, containers with garment-hanging equipment, uncleaned tank containers).