{TAIL ~ The tieback member} of this invention is used in {HEAD ~ the contingency} that the tieback threads in the casing hanger become damaged 
{ TAIL ~ The tieback member } of this invention is used in { HEAD ~ the contingency } that the tieback threads in the casing hanger become damaged
TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH