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