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

  (Normal Signing)

  Restores the option of producing plus characters (+) in numeric
  output fields.  The S descriptor counters the action of either the
  SP or SS descriptor by restoring to the processor the discretion of
  producing plus characters on an optional basis.

  This descriptor affects fields all that follow it, until an SP or
  SS is encountered.  The S descriptor affects all following I, F, E,
  D, and G editing (in the same FORMAT statement) during the
  execution of an output statement.