The bars and spaces are arranged in {HEAD ~ a plurality} of {TAIL ~ sequential groups} defining respective characters of equal width 
of
The bars and spaces are arranged in { HEAD ~ a plurality } of { TAIL ~ sequential groups } defining respective characters of equal width
OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH