To get a pvar handle, we pass in a session in MPI_T_PVAR_HANDLE_ALLOC(session, pvar_index, obj_handle, handle, count). It seems after allocation, a pvar handle should be bound to a session internally. If so, why do we need the session argument in functions such as MPI_T_pvar_read(*session*, *handle*, buf)? Is it there to facilitate the implementation to make sure *handle* is from *session*? If not, what happens if users pass in a mismatched "session, handle" pair? Thanks --Junchao Zhang