I have no idea, was the only thing I could find on the net.
On the Long wheelbase 7 series and 2007 onwards Range Rover, the edge of the glazing is similar i.e. a frame that holds the glass in place, keeps it airtight and spaced etc. When you wind the window down, it looks weird having this frame.
It's basically like a sealed unit for a house window.
Double glazing "with gap" is proven to be quieter than laminated (a la A8 D2), and this is the reason Land Rover only went with laminated side glass for a couple of years before going with proper double glazing on the Range Rover.
Pedantic? Me? Never
http://www.youtube.com/watch?v=S0RwLIWYeLI look at 0.27 sec on this clip - see the band around the glass? It's all I could find on the net!