Ensuring alignment of {HEAD ~ the data} in {TAIL ~ time} for all the subsystems is problematic 
in
Ensuring alignment of { HEAD ~ the data } in { TAIL ~ time } for all the subsystems is problematic
OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH