The Combined Nomenclature (CN), v1:2020
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=82f0fee5-2769-43bc-83fc-79117ee135ae