CPV code 73423000 designates Development of military vehicles in the Common Procurement Vocabulary (CPV 2008), the EU classification used to describe the subject of public contracts.
73423000 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 73420000 (Pre-feasibility study and technological demonstration).