To ensure proper referencing, each Close Message must include a reference to the Previous CCN above it. For Full Container Load (FCL) or back-to-back shipments where freight forwarders interact directly with the carrier, the Previous CCN will be identical to the Primary CCN (9000 series for ocean mode). However, in a co-load scenario where freight forwarders interact with other freight forwarders, the Previous CCN will be the Master Freight Forwarder CCN (8000 series for ocean mode).