wherein the A, B, C and D register {TAIL ~ values} at the beginning of the time critical path are An, Bn, Cn, Dn, and further wherein the A, B, C and D register values at the end of the time critical path are {HEAD ~ An+4}, Bn+4, Cn+4, Dn+4 
wherein the A , B , C and D register { TAIL ~ values } at the beginning of the time critical path are An , Bn , Cn , Dn , and further wherein the A , B , C and D register values at the end of the time critical path are { HEAD ~ An+4 } , Bn+4 , Cn+4 , Dn+4
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH