The classic model is associated with all versions of netCDF prior to netCDF-4.0. The enhanced model is a superset of the classic model, which closely mirrors the HDF5 data model.

Fun facts about netCDF data models:

• The Common Data Model is a conceptual model of data (not just netCDF data), originally developed as part of the netCDF-Java library.
• The enhanced data model includes groups. Each group cooresponds to a complete data file in the classic model. This the enhanced model encapsulates the classic model.
• For maximum portability of data, use the classic model.
• For very complex data sets, consider the enhanced model.
• Since the enhanced model is a superset of the classic model, a good understanding of the classic model is required, even for users of the enhanced model.

2011 Unidata NetCDF Workshop > The Two NetCDF Data Models