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direct ratio, <of an interior lighting installation>
quotient of the direct luminous flux on the working plane and the downward luminous flux of the installation
Note 1 to entry: The direct ratio has unit one.
Note 2 to entry: This entry was numbered 845-09-46 in IEC 60050-845:1987.
Note 3 to entry: This entry was numbered 17-320 in CIE S 017:2011.