gfortran -fdec options rejected

[Wolfgang Marten]

Dear all,

I installed gfortran. It works fine with both Microsoft Windows 10 and
Ubuntu Linux 16.04 LTS.

Now I have to recompile lengthy old Fortran 77 code which makes extensive
use of DEC/VAX extensions such as Structure, Record, Union, Map. This code
worked perfectly up to now (old HP-UX 11 workstation). Rewriting the code in
up-to-date Fortran would take many months which is unacceptable and probably
would generate new bugs.

Unfortunately the compiler does not accept the options -fdec -fdec-structure
-fdec-intrinsic-ints -fdec-static -fdec-math though they are documented in  
- https://gcc.gnu.org/onlinedocs/gfortran/Fortran-Dialect-Options.html
-
https://gcc.gnu.org/onlinedocs/gfortran/Extensions-implemented-in-GNU-Fortra
n.html#Extensions-implemented-in-GNU-Fortran
-
https://gcc.gnu.org/onlinedocs/gfortran/STRUCTURE-and-RECORD.html#STRUCTURE-
and-RECORD
(Links deactivated since rejected by your mail server as spam.)

What is to be done to make these compiler options work?    

Best regards
Wolfgang Marten