Generic_Operators

 An interface block can be used to define a generic operator.  The
 only procedures allowed in the interface block are functions that
 can be referenced as defined operations.  Statement format for
 initial line in block:

    INTERFACE OPERATOR (op)
    
    op  Is one of the following:
   
        A defined unary  operator (one argument) 

        A defined binary  operator (two arguments)

        An extended intrinsic operator (number of arguments 
              must be consistent with the intrinsic uses of 
              that operator)

 The functions within the interface block must have one or two
 nonoptional arguments with intent IN, and the function result must
 not be of type character with assumed length.  A defined operation
 is treated as a reference to the function.

 EXAMPLES:

   INTERFACE OPERATOR(.BAR.)
     FUNCTION BAR(A_1)
       INTEGER, INTENT(IN) :: A_1
       INTEGER :: BAR
     END FUNCTION BAR
   END INTERFACE

 The following example shows a way to reference function BAR by
 using the new operator:

   INTEGER B
   I = 4 + (.BAR. B)

 The following is an example of a procedure interface block with a
 defined operator extending an existing operator:

   INTERFACE OPERATOR(+)
     FUNCTION LGFUNC (A, B)
     LOGICAL, INTENT(IN) :: A(:), B(SIZE(A))
     LOGICAL :: LGFUNC(SIZE(A))
     END FUNCTION LGFUNC
   END INTERFACE

 The following example shows two equivalent ways to reference
 function LGFUNC:

   LOGICAL, DIMENSION(1:10) :: C, D, E
   N = 10
   E = LGFUNC(C(1:N), D(1:N))
   E = C(1:N) + D(1:N)