Another system allows an operator to vary {HEAD ~ the width} of {TAIL ~ a mark} from an initial dimension 
of
Another system allows an operator to vary { HEAD ~ the width } of { TAIL ~ a mark } from an initial dimension
OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH