Specifies to use the Compaq Fortran 77 compiler.  The default is
  to use the VSI Fortran (95/90 language) compiler.

  If you specify the /OLD_F77 qualifier, certain qualifiers
  associated with Fortran 95 and Fortran 90 features, Fortran 95 and
  90 standards checking, and certain optimization keywords will be
  ignored.

  If specified, the /OLDF77 qualifier must immediately follow the
  FORTRAN verb on the command line.  For help on Fortran 77 options,
  see HELP F77.

  If you wish to change the default compiler invoked by the FORTRAN
  command, use one of the following command definition files:

   o  SYS$LIBRARY:FORT$FORTRAN-F77.CLD

      Specifies that the FORTRAN command invokes the HP Fortran
      77 compiler and that the F90 command invokes the HP Fortran
      compiler.

   o  SYS$LIBRARY:FORT$FORTRAN-F95.CLD

      Specifies that the FORTRAN and F90 commands invoke the HP
      Fortran compiler and that the FORTRAN/OLD_F77 command invokes
      the HP Fortran 77 compiler.  This is the default.

  To change the command definition for your process, use the command:

     $ SET COMMAND SYS$LIBRARY:FORT$FORTRAN-Fxx

  where "xx" is either 77 or 95.

  To change the definition for all users on the system, use the
  command:

     $ SET COMMAND /TABLES=SYS$LIBRARY:DCLTABLES -
                   /OUTPUT=SYS$COMMON:[SYSLIB]DCLTABLES -
                   SYS$LIBRARY:FORT$FORTRAN-Fxx
     $ INSTALL REPLACE SYS$LIBRARY:DCLTABLES

  The INSTALL REPLACE command must also be executed on any other
  OpenVMS Alpha nodes of the cluster.  Users must log out and in
  again to see the new definitions.