But 30 year old Fortran code should compile and run with no problems, unless it used something non-standard, shouldn’t it? In which case, the problem is not the

But 30 year old Fortran code should compile and run with no problems, unless it used something non-standard, shouldn’t it? In which case, the problem is not the evolving Fortran standard, but the use of non-standard compiler features. “The Fortran standards committee generally refuses to break backward compatibility when Fortran is updated. This is a good thing (take that, Python), and code written decades ago can still be compiled fine today.” -- http://degenerateconic.com/backward-compatibility/ http://degenerateconic.com/backward-compatibility/