Black and white lightmap

I've generated some Lightmap, and if I click on the Litghmaps tab in the Lighting inspector, I can see a black and white texture (intensity), and a normal texture (directionality).
My question is: where are the light colors stored?

 

How is the color stored in a black and white texture?

 

I use single lightmaps (non directional) and the color is stored in the black and white light map (intensity like KEngelsoft said). For example, my sun is a bit yellow and my lightmap is actually a bit yellow and black. I tested this by making part of the lightmap pure white instead of yellowish and the terrain changed accordingly. I also threw on a splat of red to test and that part of the terrain became lit red. (there is probably some cool possibilities here)