How many netCDF data models are there?
There are only two netCDF data models, the classic model and the enhanced model (also called the netCDF-4 data model). The classic model is the simpler of the two, and is used for all data stored in classic format, 64-bit offset format, or netCDF-4 classic model format. The enhanced model (sometimes also referred to as the netCDF-4 data model) is an extension of the classic model that adds more powerful forms of data representation and data types at the expense of some additional complexity. Although data represented with the classic model can also be represented using the enhanced model, datasets that use enhanced model features, such as user-defined data types, cannot be represented with the classic model. Use of the enhanced model requires storage in the netCDF-4 format.