Transfers control from a subprogram to the calling program.  You
  can only use RETURN in a subprogram unit.  Statement format:

     RETURN [i]

     i  Is an optional integer constant or expression (such
        as 2 or I+J) indicating the position of an alternate
        return from the subprogram in the actual argument list.
        The "i" is converted to an integer value if necessary.

  The argument "i" is valid only for subroutine subprograms.  If no
  alternate return is specified or the specified alternate return
  does not exist in the actual argument list, control returns to the
  statement following the CALL statement.

                                 NOTE

          An alternate return is an  obsolescent  feature  in
          Fortran  95  and  Fortran 90.  VSI Fortran fully
          supports this feature.

  If the subprogram is a function, control returns to the statement
  containing the function reference.  If the subprogram is a
  subroutine, control returns either to the statement following the
  CALL statement, or to the label specified by the alternate return
  argument.