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