FIG 3 further illustrates the provision of {HEAD ~ a notch} 90 formed by {TAIL ~ shoulders} on the adjacent facing circumferential ends of the segments 80 
formed by
FIG 3 further illustrates the provision of { HEAD ~ a notch } 90 formed by { TAIL ~ shoulders } on the adjacent facing circumferential ends of the segments 80
OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH REL REL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH