N.Y. U.C.C. 5-104

Section 5--104. Formal requirements.\n A letter of credit, confirmation, advice, transfer, amendment, or\ncancellation may be issued in any form that is a record and is\nauthenticated:\n (a) by a signature, or\n (b) in accordance with the agreement of the parties or the standard\npractice referred to in subsection (e) of section 5--108.\n