  1.When equipped with 2-rough norm and restricted to continuous paths with
bounded variation, the area operator is a closable unbounded operator. 2.The
area defined through Riemann-Stieltjes integral is the only possible candidate
to enhance a path with vanishing 2-variation into a geometric 2-rough path.
3.Young integral is extended to p^-1+q^-1=1 by assigning a finer scale
continuity.
