(Suppress Sign)

  Causes the processor to suppress a leading plus character from any
  position where this character would otherwise be optional.  It has
  the opposite effect of the SP field descriptor.

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