New York Laws
Article 5 - Letters of Credit
5-106 - Issuance, Amendment, Cancellation, and Duration.

(a) A letter of credit is issued and becomes enforceable according to
its terms against the issuer when the issuer sends or otherwise
transmits it to the person requested to advise or to the beneficiary. A
letter of credit is revocable only if it so provides.
(b) After a letter of credit is issued, rights and obligations of a
beneficiary, applicant, confirmer, and issuer are not affected by an
amendment or cancellation to which that person has not consented except
to the extent the letter of credit provides that it is revocable or that
the issuer may amend or cancel the letter of credit without that
consent.
(c) If there is no stated expiration date or other provision that
determines its duration, a letter of credit expires one year after its
stated date of issuance or, if none is stated, after the date on which
it is issued.
(d) A letter of credit that states that it is perpetual expires five
years after its stated date of issuance, or if none is stated, after the
date on which it is issued.