27 CFR § 19.485 - Package identification numbers in production and storage.
(a) General. A proprietor must mark with a lot identification number each package of spirits filled during production or storage operations. The lot identification number must show when the package was filled and must consist of, in order, the following:
(1) The last two digits of the calendar year;
(2) An alphabetical designation for the month from “A” through “L”, representing, in order, January through December;
(3) Two digits corresponding to the day of the month; and
(4) When more than one lot is filled into packages during the same day, for successive lots after the first lot, a letter suffix sequence starting with “A” representing the second lot, with “B” representing the third lot, and so forth. For example: the first three lots filled into packages on January 2, 2002, would be identified as “02A02”, “02A02A”, and “02A02B”.
(b) Packages constituting a lot. Packages of spirits, including any remnant package, received from customs custody or filled during any one day will receive the same lot identification number, subject to the following conditions:
(1) They are of the same type and either are of the same rated capacity or are uniformly filled with the same quantity by weight or other measurement method prescribed in § 19.289;
(3) If they are filled with mingled spirits, the mingling was conducted in accordance with § 19.326; and
(4) In the case of spirits imported or brought into the United States, they are filled with imported spirits, Puerto Rican spirits or Virgin Island spirits, as applicable.
(c) Serial numbers. At the time of filling, receipt on bonded premises, or withdrawal from bond, the appropriate TTB officer may require serial numbers on packages of spirits within the same lot in conjunction with the lot identification number. The proprietor must assign temporary serial numbers to packages for control purposes when they are transferred in bond in an unsecured conveyance or gauged after tampering within the storage account.