10.2.3. Basic Fortran Support

Because Fortran 90 is (for all practical purposes) a superset of Fortran 77, Fortran 90 (and future) programs can use the original Fortran interface. The following additional requirements are added:

1. Implementations are required to provide the file mpif.h, as described in the original MPI-1 specification.
2. mpif.h must be valid and equivalent for both fixed- and free- source form.

To make mpif.h compatible with both fixed- and free-source forms, to allow automatic inclusion by preprocessors, and to allow extended fixed-form line length, it is recommended that requirement two be met by constructing mpif.h without any continuation lines. This should be possible because mpif.h contains only declarations, and because common block declarations can be split among several lines. To support Fortran 77 as well as Fortran 90, it may be necessary to eliminate all comments from mpif.h. ( End of advice to implementors.)