In this method, in the case of trapping {TAIL ~ the movement} of the rear pane in {HEAD ~ the lowering direction} is stopped and the rear pane is reversed, i.e. moved in the lifting direction 
In this method , in the case of trapping { TAIL ~ the movement } of the rear pane in { HEAD ~ the lowering direction } is stopped and the rear pane is reversed , i.e. moved in the lifting direction
OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH