Marking merchandise by specific methods, such as die stamping, cast-in-the-mold lettering, etching, or engraving, or cloth labels may be required by the Commissioner of Customs in accordance with section 304(a), Tariff Act of 1930, as amended (19 U.S.C. § 1304(a)). Notices of such rulings shall be published in the Federal Register and the Customs Bulletin.