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