a cam surface located on {HEAD ~ an exterior portion} of the tieback member in {TAIL ~ engagement} with an inner side of the locking member 
a cam surface located on { HEAD ~ an exterior portion } of the tieback member in { TAIL ~ engagement } with an inner side of the locking member
OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH REL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH