Just because it is glass does not mean it is called a window. There are either one or two WINDSHIELDS, none or two VENTS, and finally two side/two corner/and one rear WINDOW or just the two side and one rear window. Now matter how you count that it comes to either three or five windows. When you look through a telescope your looking through glass but you don't call it a window. It ended a lot of confusion when you needed a side glass replaced that you could tell the parts people that you needed either a window or a vent.

Evan