27 CFR 25.145: Tanks, vehicles, and vessels.

(a) Each brewer who transfers beer to another brewery of the same ownership (as defined in § 25.181), or who exports beer without payment of tax, as provided in § 25.203, shall plainly and durably mark each tank, tank car, tank truck, tank ship, barge, or deep tank of a vessel in accordance with paragraph (b) of this section. These marks may be placed on a label securely affixed to the route board of the container.

(b) The brewer shall mark each container with—

(1) The designation “Beer”;

(2) The brewer's name;

(3) The address of the brewery from which removed;

(4) The address of the brewery to which transferred or the marks required for exportation in part 28 of this chapter, as applicable;

(5) The date of shipment; and

(6) The quantity, expressed in barrels.