• In netCDF-4, new metadata can be added without needing to move data.
• The parts of an HDF5 file include: a "superblock", B-trees, raw data, a global heap, local heaps, and object headers, scattered around in the file.
• For how netCDF-4 is represented in terms of HDF5, see C.3 The NetCDF-4 Format in the User's Guide.
• For HDF5 format details, see HDF5 File Format Specification Version 2.0
• You don't need to know details of the format to use the netCDF-4 APIs, though some knowledge of chunking and compression is useful.
• A session tomorrow will cover HDF5 for netCDF users.

2012 Unidata NetCDF Workshop > Formats and Performance