In MPI-2 Page 13 Line 33 it says:
All MPI names have an MPI_ prefix, and all characters are
capitals.
However this statement "and all characters are capitals"
hasn't any meaning in the Fortran context, right?
My understanding (and I'll repeat again: I'm nowhere near a fortran
expert) is that fortran compilers will change subroutine/function/
variable symbols to either all upper case or all lower case (possibly
with some additional underscores). I don't know if this is a Fortran
standard thing (e.g., if the Fortran standard says that symbols are
case-insensitive), or whether it's an implementation thing.