{TAIL ~ The specified width} of {HEAD ~ a single UPC character} must, by specification, be 7 modules, each module being dark or white 
{ TAIL ~ The specified width } of { HEAD ~ a single UPC character } must , by specification , be 7 modules , each module being dark or white
TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH