The letter of creidt is an arrangement for the safe negotiation of a payment and credit transaction, esp. in connection with international deliveries of merchandise. The letter of credit covering merchandise consists of a written undertaking on the part of a bank to pay, on instructions from the buyer, a certain amount to the seller within a prescribed period and against surrender of stipulated documents covering the shipment of goods contracted for between seller and buyer, to accept said payment or to negotiate it, or to authorize another bank to make such payments or draft negotiations if the conditions are met. All instructions to open, confirm or advise of a documentary credit must list precisely the documents to be presented. Permissible documents include: bill of lading, insurance documents, trading invoice, consular invoice, certificate of origin, weight and quality certificates. A letter of credit can be revocable or irrevocable.