A more thorough explanation:

An onboard bill of lading is a document that acknowledges the receipt of goods by a carrier or shipper's agent and the contract for the transportation of those goods. It is issued by a person engaged in the business of transporting or forwarding goods. This document indicates the receipt of goods for shipment and contains the terms of the contract for the carriage of the goods agreed upon between the shipper of the goods and the shipowner.

For example, when a company ships a container of goods to another country, they will receive an onboard bill of lading from the shipping company. This document will show that the goods have been loaded onto the ship and will be transported to the destination country. The onboard bill of lading will also contain information about the terms of the transportation contract, such as the delivery date and any fees or charges.

In multimodal shipments, an onboard bill of lading may include goods loaded onto land vehicles also. This means that if the container of goods is transported by both ship and truck, the onboard bill of lading will show that the goods have been loaded onto both types of vehicles.