Section 21 WORKS OF ART, COLLECTORS’ PIECES AND ANTIQUES 97 Works of art, collectors’ pieces and antiques 97 04 Postage or revenue stamps, stamp-postmarks, first-day covers, postal stationery 97 04 00 97 04 00 00 Commodity Code Description 97 04 00 00 00 Postage or revenue stamps, stamp-postmarks, first-day covers, postal stationery (stamped