Okla. Stat. tit. 12A, § 12A-5-106: Issuance, Amendment, Cancellation, and Duration

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 (1)

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 (5) years after its stated date of issuance, or if none is

stated, after the date on which it is issued.