What is a Transportation Reference Number (TRN)?
The TRN is a reservation number assigned by the carrier to hold space on the carrier for cargo being shipped. The TRN is also known as the booking number for vessel shipments; the master air waybill number for air shipments; the bill of lading number for rail shipments’ and the freight or pro bill for truck shipments. See FTR section 30.6(b)(14).