26.97—Marking containers of wine.
Containers of wine of Puerto Rican manufacture which are to be shipped to the United States must be marked with the name of the winemaker, the serial number of the container, the kind and taxable grade of the wine, the gallon content, and the serial number of the withdrawal permit, Form 487B, prefixed by the number of such form, e.g., “487B-61-3.”