If the requirement is to read CSV files from a third party, then suggesting HDF5 isn't helpful. If the requirement is to write CSV files to send to a third par

If the requirement is to read CSV files from a third party, then suggesting HDF5 isn't helpful. If the requirement is to write CSV files to send to a third party, then suggesting HDF5 isn't helpful. So this limits the usefulness of mentioning HDF5 to when you are both the producer and consumer of the data, but that's the easy case because then you can choose anything up to and including strongly typed binary formats.