Fig. 1: Difference between Indicator lamps (bottom) and a normal Lamp (top) with light cone.
The Indicator lamps are lights added by RedLogic and require a redstone signal to illuminate. In contrast to the normal lamps or other light sources, the Indicator lamps have no light cone (shown in Fig. 1). Thereby these lights don't prevent monsters arise. There are 16 colors for the Indicator lamps (see below).
