{HEAD ~ The data blocks} are error checked by {TAIL ~ an error check unit} and the number of erroneous data blocks is stored in memory 
are error checked by
{ HEAD ~ The data blocks } are error checked by { TAIL ~ an error check unit } and the number of erroneous data blocks is stored in memory
HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH