Iw[.m] (Integer Editing)

  On input, I transfers "w" characters from the external field and
  assigns them, as an integer value, to the corresponding I/O list
  element (which must be integer or logical data type).  The external
  data must have the form of an integer constant; it cannot contain a
  decimal point or exponent field.

  If the first nonblank character of the external field is a minus
  sign, the field is treated as a negative value.  If the first
  nonblank character is a plus sign or if no sign appears in the
  field, the field is treated as a positive value.

  On output, I transfers the value of the corresponding I/O list
  element, right-justified, to an external field that is "w"
  characters long.  If the value does not fill the field, leading
  spaces are inserted; if the value is too large for the field, the
  entire field is filled with asterisks.  "w" must be large enough to
  include a possible minus sign.  If "m" is present, the external
  field consists of at least "m" digits and, if necessary, is zero
  filled on the left.