Red and green are used for normal vector rescaling - see PluginsAndObjects for more info. Blue is used as a scaling factor to change the speed of cycling. 2.0 will make the light cycle twice every second. Alpha is ignored.
RGB color is set to white. Alpha is set to brightness or 0 for off.
This light turns off when runway lights are inoperative or no airport lights are on (daytime VFR).
This light requires the object sequence number to be in a special coding - see below.
This forms a directional light - the normal vector is straight forward along the Z axis, scaled by the RG channels.
The light will flash in steps: the low two digits (0-99) of the object sequence number specify the sequence number and the top digits (100+) indicate the number of steps. So an object sequence number of 2015 means that this is the 16th light (0-based counting) of 20.
This light is only appropriate for objects being used for the rabbit component of an approach light, because it depends on x-plane to set the sequence numbers appropriately.