CV designation system
For example: CV4004
Base format is 'Cvxxxx', where xxxx is an 4 digits number as type code.
This designation has used by the British Military to codify vacuum tubes, gas tubes, and
latterly, some semiconductor devices.
CV numbers can be directly mapped onto NATO numbers, as 5960-XX-000-YYYY where XX is the
country code, and YYYY is the CV number. For example, 5960-99-000-4004=CV4004 (12AX7WA),
with 99 indicating country of origin as UK.