The E descriptor is used in the form Ew.d or Ew.d Ee
in order to present REAL values with an exponent part. w is the width of
the field and d is the number of digits to be presented after the
decimal point in the mantissa. In the second form of the E descriptor, the
positive integer e is the number of digits in the exponent part. The
field is padded out with leading spaces if required. w will need to be
at least d+7 in order to provide spaces for the other characters. If the
field width is too small for the value to be output, then it is filled with
asterisks in order to flag the error.
The EN (engineering) descriptor is identical to the E descriptor apart from the
fact that the exponent is always presented as a multiple of 3.
The ES (scientific) descriptor is identical to the E descriptor apart from the
fact that a non-zero mantissa is always presented as a value greater than or
equal to 1 and less than 10.