How does halo.bmp works?

Hello! I tried searching but didn't find an answer.

Doeas anyone knows how halo.bmp works?

I mean, there are four shining lights in the bitmap and i would like to know each one what affect what (runways, beacon, strobe...)

I know i could found it out my self trying and testing, but if only someone just knows... I could save hours of trials.

Thanks a lot!