In the case of trapping, the movement of {TAIL ~ the rear pane} in the lowering direction is stopped and the rear pane is moved in {HEAD ~ the lifting direction}  
In the case of trapping , the movement of { TAIL ~ the rear pane } in the lowering direction is stopped and the rear pane is moved in { HEAD ~ the lifting direction }
OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH