In {TAIL ~ a third aspect}, the present invention provides special retention means for firmly, but flexibly, retaining the side windows in {HEAD ~ the frame} 
In { TAIL ~ a third aspect } , the present invention provides special retention means for firmly , but flexibly , retaining the side windows in { HEAD ~ the frame }
OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD