Existing:

MPI_FILE_READ_AT   - MPI_FILE_READ_AT_ALL
MPI_FILE_WRITE_AT  - MPI_FILE_WRITE_AT_ALL
MPI_FILE_IREAD_AT  - MPI_FILE_IREAD_AT_ALL
MPI_FILE_IWRITE_AT - MPI_FILE_IWRITE_AT_ALL


MPI_FILE_READ   - MPI_FILE_READ_ALL
MPI_FILE_WRITE  - MPI_FILE_WRITE_ALL
MPI_FILE_IREAD  - MPI_FILE_IREAD_ALL
MPI_FILE_IWRITE - MPI_FILE_IWRITE_ALL


Proposed:
    Discussion points:
        - Tempting to add 'offset' for buffer, to make parameters symmetric
            - Probably not though...
        - No "count" parameters, only derived datatypes
            - Sidesteps the "big count" discussion
        - Naming
            - 't' prefix? (for 'type read', etc)
                e.g. MPI_File_tread_at()
            - 't' suffix? (like "big count", for 'type read', etc)
                e.g. MPI_File_read_at_t()
            - 'dt' prefix / suffix? (for 'datatype read', etc)
                e.g. MPI_File_dtread_at() / MPI_File_read_at_dt()
            - Other ideas?
        - No shared file pointer versions

int MPI_File_new_read_at(MPI_File fh,
                       MPI_Offset offset,
                       MPI_Datatype file_datatype,
                       void *buf,
                       MPI_Datatype buf_datatype,
                       MPI_Status *status);
int MPI_File_new_read_at_all(MPI_File fh,
                       MPI_Offset offset,
                       MPI_Datatype file_datatype,
                       void *buf,
                       MPI_Datatype buf_datatype,
                       MPI_Status *status);

int MPI_File_new_write_at(MPI_File fh,
                       MPI_Offset offset,
                       MPI_Datatype file_datatype,
                       const void *buf,
                       MPI_Datatype buf_datatype,
                       MPI_Status *status);
int MPI_File_new_write_at_all(MPI_File fh,
                       MPI_Offset offset,
                       MPI_Datatype file_datatype,
                       const void *buf,
                       MPI_Datatype buf_datatype,
                       MPI_Status *status);

int MPI_File_new_iread_at(MPI_File fh,
                       MPI_Offset offset,
                       MPI_Datatype file_datatype,
                       void *buf,
                       MPI_Datatype buf_datatype,
                       MPI_Request *request);
int MPI_File_new_iread_at_all(MPI_File fh,
                       MPI_Offset offset,
                       MPI_Datatype file_datatype,
                       void *buf,
                       MPI_Datatype buf_datatype,
                       MPI_Request *request);

int MPI_File_new_iwrite_at(MPI_File fh,
                       MPI_Offset offset,
                       MPI_Datatype file_datatype,
                       const void *buf,
                       MPI_Datatype buf_datatype,
                       MPI_Request *request);
int MPI_File_new_iwrite_at_all(MPI_File fh,
                       MPI_Offset offset,
                       MPI_Datatype file_datatype,
                       const void *buf,
                       MPI_Datatype buf_datatype,
                       MPI_Request *request);


int MPI_File_new_read(MPI_File fh,
                       MPI_Datatype file_datatype,
                       void *buf,
                       MPI_Datatype buf_datatype,
                       MPI_Status *status);
int MPI_File_new_read_all(MPI_File fh,
                       MPI_Datatype file_datatype,
                       void *buf,
                       MPI_Datatype buf_datatype,
                       MPI_Status *status);

int MPI_File_new_write(MPI_File fh,
                       MPI_Datatype file_datatype,
                       const void *buf,
                       MPI_Datatype buf_datatype,
                       MPI_Status *status);
int MPI_File_new_write_all(MPI_File fh,
                       MPI_Datatype file_datatype,
                       const void *buf,
                       MPI_Datatype buf_datatype,
                       MPI_Status *status);

int MPI_File_new_iread(MPI_File fh,
                       MPI_Datatype file_datatype,
                       void *buf,
                       MPI_Datatype buf_datatype,
                       MPI_Request *request);
int MPI_File_new_iread_all(MPI_File fh,
                       MPI_Datatype file_datatype,
                       void *buf,
                       MPI_Datatype buf_datatype,
                       MPI_Request *request);

int MPI_File_new_iwrite(MPI_File fh,
                       MPI_Datatype file_datatype,
                       const void *buf,
                       MPI_Datatype buf_datatype,
                       MPI_Request *request);
int MPI_File_new_iwrite_all(MPI_File fh,
                       MPI_Datatype file_datatype,
                       const void *buf,
                       MPI_Datatype buf_datatype,
                       MPI_Request *request);