CDL extended for netCDF enhanced data model

15.0 CDL extended for netCDF enhanced data model

CDL syntax has been extended to handle enhanced data model's primitive types, groups, and user-defined types

Rather than cover details of the extended syntax, we'll just look at some examples.

ncdump and ncgen both support CDL extended to cover the netCDF-4 enhanced data model
CDL now has the following new elements:
- extended set of atomic types
- user-defined types
- typed attributes
- groups
- "special" attributes
Details are in the ncgen man page reference and this presentation