This synchronization mechanism insures that {HEAD ~ the desired output} which is presented to the foreground program is in {TAIL ~ fact} based on real time data 
This synchronization mechanism insures that { HEAD ~ the desired output } which is presented to the foreground program is in { TAIL ~ fact } based on real time data
OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH REL REL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH