Several Questions.

[Dominique d'Humières]

> Question 1.  How do I join the gfortran users mailing list?

If you want to subscribe to the list, go to https://gcc.gnu.org/lists.html#subscribe and select fortran.

> comp@AbNormal:~/Apps/gFortran$ ./mt3dm1 B1.prn
> At line 18 of file MT3DM1.FOR (unit = 1)
> Fortran runtime error: Cannot open file '': No such file or directory

As usual, you need to post the code in order to get some help.

Welcome on board!

Dominique