Is there a rule for tempered glass?

[Lew Silverman]

I think that is "tempered" glass - notice how it breaks into small pieces. Regular glass cracks in much larger and more dangerous pieces. The windshields are made with a laminated safety glass so you don't get showered with glass shards, although I think part of the reason is to keep the occupants from going through the windshield, as it tends to pop-out in one piece.

Lew