The Combined Nomenclature (CN), v1:2021
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=6b82e360-3b3b-4ca9-8ead-47dd359f111d