CPV code 50311400 designates Maintenance and repair of calculators and accounting machinery in the Common Procurement Vocabulary (CPV 2008), the EU classification used to describe the subject of public contracts.
50311400 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 50311000 (Maintenance and repair of office accounting machinery).