Section 13,31: EXTERNAL

 Specifies that a name is a global symbol defined outside the
 program unit.  Statement format:

    EXTERNAL v[,v]...
    EXTERNAL *v[,*v]...

    v  Is the symbolic name of a user-supplied subprogram, or
       the name of a dummy argument associated with the name
       of a subprogram.  If you name an intrinsic subprogram, 
       that name becomes disassociated from the intrinsic
       subprogram and is assumed to be the name of an external 
       element.  (The INTRINSIC statement allows intrinsic
       function names to be used as arguments.)

    *  Is permitted only with the -nof77 (/NOF77 on VMS 
       systems) option.

 You must use EXTERNAL statements in the following cases:

  -  To identify subprogram or entry point names passed as actual
     arguments

  -  To identify a block data program unit that will reside in a
     library module not explicitly referenced at link time.


 You do not need to use an EXTERNAL statement to identify a
 subprogram or entry point name used as the object of a CALL
 statement or function reference; these names are recognized as
 external implicitly.