Section: 13.0 Groups and User Defined Types in NetCDF-4

13.0 Groups and User Defined Types in NetCDF-4

NetCDF-4 group and user defined types are powerful new netCDF-4 features.

In netCDF-4 files, dimensions, attributes, and variables can be organized into heirarchical groups. Each group is like its own netCDF-3 file.
Dimensions are inherited downward, that is, a dimension defined in a group is visible to all sub-groups, and their sub-groups, etc.
To scan a file with groups, a recursive function is needed.
User-defined types may be defined in any group, and are visible everywhere in the file.
There are four kinds of user defined types, compound, variable length array, enumeration, and opaque.
A user defined type must be defined before a variable or attribute using the type is defined.