 for CRTs, receiving and transmitting valves used in army equipments, "NC~", "NR~" and "NT~" similarly for navy equipments and "VCR~", "VR~" and "VT~" etc.for air force equipments), in which three separate designations could in principle apply to the same valve (which often had at least one prototype commercial designation as well).These numbers generally have identical equivalents in both the North American, RETMA, and West European, Mullard–Philips, systems but they bear no resemblance to the assigned "CV" number.