/sys$common/syshlp/helplib.hlb FORTRAN, Format Specifiers, P, D field descriptor  *Conan The Librarian (sorry for the slow response - running on an old VAX)

  nPDw.d

  On output, the basic real constant part of the I/O list element is
  multiplied by 10**n, and "n" is subtracted from the exponent.  For
  a positive scale factor, "n" must be less than (d+2) or an output
  conversion error occurs.  Thus, a positive scale factor moves the
  decimal point to the right and decreases the exponent; a negative
  scale factor moves the decimal point to the left and increases the
  exponent.