Having an Xdmf file alongside is nice, but the breaking changes between v2 and v3 are very annoying. And I understand the want to have few external dependencies

Having an Xdmf file alongside is nice, but the breaking changes between v2 and v3 are very annoying. And I understand the want to have few external dependencies, but at least HDF5 is straight forward to compile and available as a pre-compiled module on all supercomputers that I have ever seen.