U.S. Customs agents and port authorities send the 350 transaction set to ocean carriers, freight forwarders, importers, and other trade partners to communicate the status of shipments moving through U.S. ports. This transaction set is typically transmitted in response to manifest submissions or status inquiry requests and provides real-time updates on customs clearance progress and cargo disposition. The M10 segment conveys manifest identifying information that links the status update to a specific shipment record, while the P4 segment specifies the U.S. port location involved, and the X4 segment records customs release information and clearance status.

When an importer like Global Logistics Corp. submits an ocean manifest through its carrier Horizon Shipping Lines, Horizon subsequently uses the 350 transaction set to notify Global Logistics Corp. that their container has arrived at the Port of Los Angeles, has been examined by U.S. Customs, and is being held pending duty payment. The P4 loop identifies the Los Angeles port, the X4 loop details the specific release conditions and any outstanding requirements, and supporting K1 remarks segments clarify any inspection findings or documentation issues that must be resolved before cargo can be released to the importer.