All stamps shall be canceled in ink, with the license number assigned to each licensee clearly indicated, before the cigarettes to which the stamps are affixed are offered for sale.
Stamps may be canceled before or after they are affixed.
All canceling devices shall show the license number of the licensee.
Cancellation of stamps shall be accomplished so that the license number will be legible.
It shall not be necessary to cancel meter imprinted stamps which carry the identifying number of the licensee.
D.C. Mun. Regs. tit. 9, r. 9-1006