This transaction set enables ocean freight shippers and freight forwarders to request cargo space reservations with ocean carriers. Shippers or their logistics partners send the X12 300 to carriers or their booking systems to reserve container capacity for upcoming ocean shipments. The B1 (Beginning Segment for Booking or Pick-up/Delivery) segment establishes the booking request parameters, while the Y1 (Space Reservation Request) segment formally initiates the reservation. The N1 loop identifies the parties involved—such as the shipper, consignee, and notify party—with their contact and address details provided through supporting segments like G61 (Contact) and N3 (Address Information).

For example, ABC Logistics submits an X12 300 to Pacific Shipping Lines to book container space for exporting electronics components from Los Angeles to Shanghai. The submission includes specific details in the R4 loop identifying the Los Angeles port as the origin and Shanghai as the destination, with requested dates and equipment specifications in the LX loop detailing two twenty-foot containers needed for the shipment. The shipper’s contact information and the consignee’s Singapore address are populated in the N1 sections, enabling Pacific Shipping Lines to confirm the reservation and provide booking confirmation details back to ABC Logistics.