In addition to the documents required for reimbursement, a bank shall retain in its files for a period of at least 3 years and shall make available to USAID promptly upon request a copy of any of the following documents which may pertain to an USAID-financed transaction:

(a) Each letter of credit issued, confirmed, or advised by it, together with any extension or modification thereof;

(b) Payment instructions received from the approved applicant;

(c) Each application and agreement relating to such letter of credit or instructions for payment, together with any extension or modification thereof;

(d) A detailed advice of the interest, commissions, expenses, or other items charged by it in connection with each such letter of credit or payment instructions.