 64   55+1     8           3 + 14 + 2 = 19 (VAX)
            64   52       11          3 + 13 + 3 = 19 (IEEE)

            The base 16 ``scientific notation'' character string
            produced by this routine will be left justified and
            consist of a contiguous sequence of characters with one
            of the following formats:

                (1)   h h h h  ... h ^H H  ... H
                       1 2 3 4      n  1 2      m

                (2)   -h h h h  ... h ^H H  ... H
               