The Combined Nomenclature (CN), v1:2020
4907 00: 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; stamp-impressed paper; banknotes; cheque forms; stock, share or bond certificates and similar documents of title
https://www.dst.dk/en/Statistik/dokumentation/nomenklaturer/kn?id=82f0fee5-2769-43bc-83fc-79117ee135ae