| quotient of the total luminous flux of the luminaire, measured under specified practical conditions with its own lamp(s) and equipment, and the sum of the individual luminous fluxes of the same lamp(s) when operated outside the luminaire with the same equipment, under specified conditions Note 1 to entry: For luminaires using incandescent lamps only, the optical light output ratio and the light output ratio are the same in practice. Note 2 to entry: The light output ratio has unit one. Note 3 to entry: This entry was numbered 845-09-39 in IEC 60050-845:1987. Note 4 to entry: This note applies to the French language only.
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