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