int MPI_Send (const void *buf, int count, MPI_Datatype datatype, int dest, int tag, MPI_Comm comm);
int MPI_Bsend (const void *buf, int count, MPI_Datatype datatype, int dest, int tag, MPI_Comm comm);
int MPI_Ssend (const void *buf, int count, MPI_Datatype datatype, int dest, int tag, MPI_Comm comm);
int MPI_Rsend (const void *buf, int count, MPI_Datatype datatype, int dest, int tag, MPI_Comm comm);

int MPI_Buffer_attach (void *buffer, int size);
int MPI_Buffer_attach_c (void *buffer, MPI_Count size);

int MPI_Buffer_detach (void *buffer_addr, int *size);
int MPI_Buffer_detach_c (void *buffer_addr, MPI_Count *size);

int MPI_Isend (
    const void *buf, int count, MPI_Datatype datatype,
    int dest, int tag, MPI_Comm comm,
    MPI_Request *request);
int MPI_Isend_c (
    const void *buf, MPI_Count count, MPI_Datatype datatype,
    int dest, int tag, MPI_Comm comm,
    MPI_Request *request);

int MPI_Ibsend (...);
int MPI_Issend (...);
int MPI_Irsend (...);

int MPI_Irecv (
    void *buf, int count, MPI_Datatype datatype,
    int source, int tag, MPI_Comm comm,
    MPI_Request *request);
int MPI_Irecv_c (
    void *buf, MPI_Count count, MPI_Datatype datatype,
    int source, int tag, MPI_Comm comm,
    MPI_Request *request);

int MPI_Iprobe (int source, int tag, MPI_Comm comm, int *flag, MPI_Status *status);
int MPI_Improbe (int source, int tag, MPI_Comm comm, int *flag, MPI_Message *message, MPI_Status *status);
int MPI_Imrecv (void *buf, int count, MPI_Datatype datatype, MPI_Message *message, MPI_Request *request);
int MPI_Imrecv_c (void *buf, MPI_Count count, MPI_Datatype datatype, MPI_Message *message, MPI_Request *request);

int MPI_Wait (MPI_Request *request, MPI_Status *status);
int MPI_Waitany (int count, MPI_Request array_of_requests [], int *index, MPI_Status *status);
int MPI_Waitall (int count, MPI_Request array_of_requests [], MPI_Status array_of_statuses []);
int MPI_Waitsome (int incount, MPI_Request array_of_requests [], int *outcount, int array_of_indices [], MPI_Status array_of_statuses []);

int MPI_Test (MPI_Request *request, int *flag, MPI_Status *status);
int MPI_Testany (int count, MPI_Request array_of_requests [], int *index, int *flag, MPI_Status *status);
int MPI_Testall (int count, MPI_Request array_of_requests [], int *flag, MPI_Status array_of_statuses []);
int MPI_Testsome (int incount, MPI_Request array_of_requests [], int *outcount, int array_of_indices [], MPI_Status array_of_statuses []);

int MPI_Request_free (MPI_Request *request);

int MPI_Request_get_status (MPI_Request request, int *flag, MPI_Status *status);

int MPI_Cancel (MPI_Request *request);

// Persistent communication requests serve to efficiently initiate repetitive communication.

int MPI_Send_init_c (
    const void *buf, MPI_Count count, MPI_Datatype datatype,
    int dest, int tag, MPI_Comm comm,
    MPI_Request *request);

int MPI_Recv_init_c (
    void *buf, MPI_Count count, MPI_Datatype datatype,
    int source, int tag, MPI_Comm comm,
    MPI_Request *request);

int MPI_Start (MPI_Request *request);
int MPI_Startall (int count, MPI_Request array_of_requests []);

// Partitioned communication requests deliver message content in independent partitions.

int MPI_Psend_init (
    const void *buf, int partitions, MPI_Count count, MPI_Datatype datatype,
    int dest, int tag, MPI_Comm comm, MPI_Info info,
    MPI_Request *request);

int MPI_Precv_init (
    void *buf, int partitions, MPI_Count count, MPI_Datatype datatype,
    int source, int tag, MPI_Comm comm, MPI_Info info,
    MPI_Request *request);

int MPI_Start (MPI_Request *request);

int MPI_Pready (int partition, MPI_Request request);
int MPI_Pready_range (int partition_low, int partition_high, MPI_Request request);
int MPI_Pready_list (int length, const int array_of_partitions [], MPI_Request request);

int MPI_Wait (...);