Back in the mid-90's, there was no "bool" C type. But since C99, there has been. So we should have an MPI_BOOL type. The point was made to me today, however, that the C "bool" type and the C++ "bool" type may not be compatible -- so MPI_BOOL and MPI::BOOL may actually represent different things. (I don't propose a solution :-) -- I just bring up the topic to be considered for 2.2...) -- Jeff Squyres Cisco Systems