On Aug 24 2012, Jeremiah Willcock wrote:

Forbidding use as a local name is important if you want to use that name as a macro in C or C++ (or Fortran with a CPP-like preprocessor). Thus, it might make sense to do that for at least some names as well, at least for the C and mpif.h bindings.

It is needed only in a translation unit (C) or program unit (Fortran) where a MPI module is used or a MPI header is included. There is no neeed to restrict it in other parts of the code. However, forbidding it being done everywhere isn't a major restriction. Regards, Nick Maclaren.