There should be no light source (direct or reflected) in the immediate surrounding area of the visual display device that is of substantially greater luminance than the visual display device screen.
Additional Information: Outside the immediate display area, but still in the visual field of the user, the luminance from other light sources that subtend an arc of greater than 5 degrees should: (1) not exceed 10 times the average screen luminance for negative-polarity screens (bright characters on dark background), and (2) not exceed 3 times the average screen luminance for positive-polarity screens (dark characters on bright background). For negative-polarity screens, the best visual performance occurs when the background luminance is approximately 5 times the average screen luminance. For positive-polarity screens, the best visual performance is obtained when the background luminance is approximately equal to the average screen luminance. 0700, 5908, 100