What is the “enhanced data model” of netCDF-4, and how does it differ from the netCDF-3 classic data model?
The enhanced model (sometimes referred to as the netCDF-4 data model) is an extension to the classic model that adds more powerful forms of data representation and data types at the expense of some additional complexity. Specifically, it adds six new primitive data types, four kinds of user-defined data types, multiple unlimited dimensions, and groups to organize data hierarchically and provide scopes for names. A picture of the enhanced data model, with the extensions to the classic model highlighted in red, is available from the online netCDF workshop. Although data represented with the classic model can also be represented using the enhanced model, datasets that use features of the enhanced model, such as user-defined data types, cannot be represented with the classic model. Use of added features of the enhanced model requires that data be stored in the netCDF-4 format.
