google tempered glass, and you will find a lot of info on how to recognize it.
Do not attempt to drill tempered as was stated.
take a look at this:
http://www.salt-city.org/showthread....ss-is-tempered
and
http://glass-fish-tanks.com/how-to-t...empered-glass/
If I go into my car in bright sunlight, and look through the rear window, while wearing polarized sunglasses, I find that there are light and dark patches in the rear windowe. Ergo, tempered glass