{TAIL ~ The first edge} is pressed against {HEAD ~ the first rail element} through a first protruding portion of the first edge 
{ TAIL ~ The first edge } is pressed against { HEAD ~ the first rail element } through a first protruding portion of the first edge
TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH