Green means yes

I feel like such a hick for posting this because I'm sure they're common in more developed countries, but I just had to because I was actually delighted when I realized what they were. I noticed them on the ceiling of the parking building when we last went to an SM Supermall, and it took me several seconds before I understood what they were for. A green light means that the parking space is free and a red light means that a car's parked there. Now, drivers don't have to crawl through all the lanes looking for a free slot; just one look at the lights and they'll know whether they can park on that level or move on to the next. Isn't that so clever? I doubt if they'll help ease the awful traffic around Manila's humongous malls during weekends though.