valgustus valgustite abil, mille valgustugevusjaotus on selline, et lõpmata suureks loetavale tööpinnale langeva valgusvoo osa valgusti koguvalgusvoost on 40 % kuni 60 %, lighting by means of luminaires having a distribution of luminous intensity such that the fraction of the emitted luminous flux directly reaching the working plane, assumed to be of infinite extent, is 40 % to 60 %