Built-in functions perform utility operations that are useful in
  communicating with subprograms written in languages other than
  Fortran.

  See also Intrinsics.

1  –  %LOC

  %LOC (arg)
  Returns the internal address of a storage item.  The argument can
  be a variable, an expression, or the name of a procedure.  (It must
  not be the name of an internal procedure or statement function.) It
  can be of any data type.  The result is an INTEGER*8 data type.

  In the case of global symbolic constants, %LOC returns the value of
  the constant rather than an address.

  The %LOC built-in function serves the same purpose as the LOC
  intrinsic.

2  –  %REF

  %REF (arg)

  Forces an actual argument in a CALL statement or function reference
  to be passed by reference:  the address of the argument is passed
  to the subprogram.  By default, Fortran passes all numeric values
  by reference.

3  –  %VAL

  %VAL (arg)

  Forces an actual argument in a CALL statement or function reference
  to be passed by value.  The argument is passed as a 64-bit immediate
  value.  If "arg" is integer (or logical) and less than 64 bits in
  size, it is sign-extended to a 64-bit value.

  When a complex argument is passed, two 64-bit values (one containing
  the real part, the other containing the imaginary part) are passed
  by immediate value.

4  –  %DESCR

  %DESCR (arg)

  Forces an actual argument in a CALL statement or function reference
  to be passed by descriptor:  the address of a descriptor of the
  argument is passed to the subprogram.  By default, Fortran passes
  all character values by descriptor.