The notches hence cooperate with the pins to serve {HEAD ~ the above discussed functions} of {TAIL ~ the pins} 
The notches hence cooperate with the pins to serve { HEAD ~ the above discussed functions } of { TAIL ~ the pins }
OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL