{HEAD ~ The transmission data length} is set to {TAIL ~ the arbitrary data length}, and thereafter an error detecting code for all the data is added therewith 
is set to
{ HEAD ~ The transmission data length } is set to { TAIL ~ the arbitrary data length } , and thereafter an error detecting code for all the data is added therewith
HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH