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