Radar systems operate in frequency bands that since World War II have been identified by letter designations. Over a period of time these frequencies and their associated letter-band designations have been fixed by usage. In order to recognize and preserve accepted usage, this standard defines the letter-band nomenclature to be used as a convenience for describing the frequency in which radar operates. It should be cautioned that these are not a substitute for the specific frequency limits of a radar, nor is it meant that these letter bands be applied to other than radar.