27 C.F.R. § 20.177
(b) When specially denatured spirits are packaged in unlabeled containers, the dealer shall apply the required marks to an exposed surface of the case. The case shall be constructed so that the portion bearing the marks will remain securely attached to the encased container until all the spirits have been removed. A statement reading “Do not remove inner container until emptied,” or of similar meaning, shall be placed on the portion of the case bearing the marks.
(Sec. 201, Pub. L. 85-859, 72 Stat. 1360, as amended (26 U.S.C. 5206))
[T.D. ATF-199, 50 FR 9162, Mar. 6, 1985, as amended at T.D. ATF-476, 67 FR 17939, Apr. 12, 2002]