XBT_PUBLIC_DATA(MPI_Datatype) MPI_2DOUBLE;
XBT_PUBLIC_DATA(MPI_Datatype) MPI_2LONG;//only for compatibility with Fortran
+XBT_PUBLIC_DATA(MPI_Datatype) MPI_REAL;
XBT_PUBLIC_DATA(MPI_Datatype) MPI_REAL4;
XBT_PUBLIC_DATA(MPI_Datatype) MPI_REAL8;
XBT_PUBLIC_DATA(MPI_Datatype) MPI_REAL16;