This is actually a contract between the carrier and the seller. A straight bill of lading is non-negotiable, but the negotiable or shipper's order bill of lading can be bought, sold, or traded while goods are in transit and used for letter of credit transactions. Buyers use the document as proof of ownership when taking possession of the goods. A commercial invoice describing the contents is necessary for both importer and exporter. In addition, it shows the payment terms and delivery terms and addresses of the shipper and seller.
Exporters use the invoice to prove ownership and secure payment.
The description of goods must exactly match the letter of credit or other documents required for payment. Some government agencies use this invoice to assess customs duties. Some countries require a consular invoice which can be obtained from the country's consulate. Export Packing List. The export packing list itemizes the contents of each individual package and indicates the package type, i.e. box, crate, drum, or carton.