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