The Combined Nomenclature (CN), v1:2019
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=ec3af576-673e-42d6-892f-12eb18291831