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