FYI - HDF5 doesn’t use this mechanism for type conversions between memory and a file. Nor does any other I/O library that I know of. Also, searching on Github (https://github.com/search?p=2&q=MPI_Register_datarep&type=Code) is only turning up implementations of it and tests for it, as far as the first bunch of search results display. (But there’s 100 pages, so I haven’t looked at all of them :-) Quincey On Mar 3, 2023, at 8:26 AM, Jeff Hammond via mpi-forum <[email protected]> wrote: CAUTION: This email originated from outside of the organization. Do not click links or open attachments unless you can confirm the sender and know the content is safe. I can't find these in the MPICH test suite or anywhere else on the internet, except in contexts where they are included because they are part of the MPI API. These functions have been in MPI since 2.1, i.e. 2008. If there is no usage after 15 years, we should deprecate these functions. As best I can tell, they are nontrivial to implement, so their existence is a distraction for anyone wishing to apply their creative energy to MPI I/O. Jeff -- Jeff Hammond [email protected]<mailto:[email protected]> http://jeffhammond.github.io/ _______________________________________________ mpi-forum mailing list [email protected] https://lists.mpi-forum.org/mailman/listinfo/mpi-forum