The Combined Nomenclature (CN), v1:2021
4907 00 10: Unused postage, revenue or similar stamps of current or new issue in the country in which they have, or will have, a recognised face value
https://www.dst.dk/en/Statistik/dokumentation/nomenklaturer/kn?id=6b82e360-3b3b-4ca9-8ead-47dd359f111d