Note 1 to entry: If the wavelength is used to characterize a monochromatic radiation, the medium has to be stated.

Note 2 to entry: In practice, monochromatic radiation is radiation of a very small range of frequencies or wavelengths that can be described by stating a single frequency or wavelength.

Note 3 to entry: This entry was numbered 845-01-07 in IEC 60050-845:1987.