The Combined Nomenclature (CN), v1:2024
8604 00 00: Railway or tramway maintenance or service vehicles, whether or not self-propelled, e.g., workshops, cranes, ballast tampers, trackliners, testing coaches and track inspection vehicles
https://www.dst.dk/en/Statistik/dokumentation/nomenklaturer/kn?id=ff35b666-b08b-41b5-bea1-78e213f89ca8