CPV code 34621200 designates Railway maintenance or service vehicles in the Common Procurement Vocabulary (CPV 2008), the EU classification used to describe the subject of public contracts.
34621200 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 34621000 (Railway maintenance or service vehicles, and railway freight wagons).