A closed indent is a foreign order which instructs an agent to buy certain goods from a particular supplier. It is a type oftrade document used in international commerce. An open indent, on the other hand, gives the agent discretion in thechoice of supplier. A letter of credit is a letter from a bank guaranteeing that a buyer's payment to a seller will bereceived on time and for the correct amount, while a letter of enquiry is a formal method of requesting information.