VMS Help FORTRAN, Built-in Functions  *Conan The Librarian (sorry for the slow response - running on an old VAX)

1 - %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.

2 - %LOC

  %LOC (arg)
  Returns the actual storage address of a data element.  The argument
  can be any data value.  The result is an INTEGER*4 data type.  In
  the case of global symbols, %LOC returns the value of the symbol
  rather than its address.

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

3 - %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.

4 - %VAL

  %VAL (arg)
  Forces an actual argument in a CALL statement or function reference
  to be passed by value:  the actual value of the argument is passed
  to the subprogram.  The argument must be 32 bits in size or less.
  If the argument is less than 32 bits in size, it is sign-extended
  to that size.