A constructed datatype must be committed to the system before it can be used in a communication. The constructed datatype is committed with a call to MPI_TYPE_COMMIT. (There is no need to commit basic datatypes; they are pre-committed.) It can then be used in any number of communications. The form of MPI_TYPE_COMMIT is:

• C

  int MPI_Type_commit (MPI_datatype *datatype)
  

• FORTRAN

  MPI_TYPE_COMMIT (DATATYPE, MPIERROR)
    INTEGER DATATYPE, MPIERROR