Section: 12.1 Introduction to NetCDF-4 Features

12.1 Introduction to NetCDF-4 Features

There are many new features in netCDF-4.

To get a netCDF-4/HDF5 file, create a file with the NETCDF4 flag:
```
      if (nc_create(FILE_NAME, NC_NETCDF4, &ncid)) ERR;
```
Without the NETCDF4 create flag, the classic format is used, and netCDF-4 new features are not allowed. This means existing code will not change when recompiled with netCDF-4.
The netCDF data model has been expanded in netCDF-4, and includes object which were not included before. Functions have been added to the API to handle groups, user-defined types, etc.
The examples in the distribution all work well with netCDF-4, but there are, as yet, few examples that demonstrate new netCDF-4 features.
Best place to look are the test files in the libsrc4 directory. There are two types of tests in this directory:
- tst_h_*.c programs - test HDF5 directly
- tst_*.c programs - test new netCDF-4 features
We welcome user-contributed examples which reflect the use of netCDF in the real world.
The new featues in netCDF-4 require some explorarion on the part of the user community.