downward light output ratio
quotient of the downward flux of a luminaire, measured under specified practical conditions with its own lamps and equipment, and the sum of the individual luminous fluxes of the same lamps when operated outside the luminaire with the same equipment, under specified conditions
Note 1 to entry: The downward light output ratio has unit one.
Note 2 to entry: This entry was numbered 845-09-40 in IEC 60050-845:1987.
Note 3 to entry: This entry was numbered 17-352 and 17-344 in CIE S 017:2011.