Format is CV followed by up to 5 digits, e.g. CV4004. Used by the British Military to codify vacuum tubes, gas tubes, and latterly, some semiconductor devices.

• CV后接数字（最多为五位）的形式，例如CV4004，为英军所采用的编号格式。用于真空管、充气管，以及后来部分半导体器件的编号。