CPV code 55260000 designates Sleeping-car services in the Common Procurement Vocabulary (CPV 2008), the EU classification used to describe the subject of public contracts.
55260000 is a leaf code — the most specific level of its branch — so it can be used directly as the main CPV code of a contract notice. If it does not quite fit, check the neighbouring codes under 55200000 (Camping sites and other non-hotel accommodation).