Constant <float> Linear <float> Quadratic <float> These three values determine how the intensity of the emitted light falls off over distance. See Constant-Linear-Quadratic Falloff. 50 percent falloff distance <string> 0 percent falloff distance <string> Distances at which brightness should have fallen to 50% and (1/256)% respectively. Overrides Linear/Constant/Quadratic parameters if non-zero.
Set them to the distances you wish the light to fall off to, and how you want it to fall off.