C.2 The NetCDF-4 Classic Model Format
Every classic and 64-bit offset file can be represented as a netCDF-4
file, with no loss of information. There are some significant
benefits to using the simpler netCDF classic model with the netCDF-4
file format. For example, software that writes or reads classic model
data can write or read netCDF-4 classic model format data by
recompiling/relinking to a netCDF-4 API library, with no or only
trivial changes needed to the program source code. The netCDF-4
classic model format supports this usage by enforcing rules on what
functions may be called to store data in the file, to make sure its
data can be read by older netCDF applications (when relinked to a netCDF-4
library).
Writing data in this format prevents use of enhanced model features
such as groups, added primitive types not available in the classic
model, and user-defined types. However performance features of the
netCDF-4 formats that do not require additional features of the
enhanced model, such as per-variable compression and chunking,
efficient dynamic schema changes, and larger variable size limits,
offer potentially significant performance improvements to readers of
data stored in this format, without requiring program changes.
