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