quotient of transmitted radiant flux,
Note 1 to entry: Transmittance is also defined spectrally in terms of wavelength, in which case, "spectral" is added before the quantity name.
Note 2 to entry: Due to energy conservation,
Note 3 to entry: Transmittance,
Note 4 to entry: The transmittance has unit one.
Note 5 to entry: This entry was numbered 845-04-59 in IEC 60050-845:1987.
Note 6 to entry: This entry was numbered 17-1337 in CIE S 017:2011.