Let's look at the dimensions, variables, and attributes from the netCDF file co2.nc:

ncdump -h co2.nc

netcdf co2 {
dimensions:
	T = 456 ;
variables:
	float T(T) ;
		T:units = "months since 1960-01-01" ;
	float co2(T) ;
		co2:long_name = "CO2 concentration by volume" ;
		co2:units = "1.0e-6" ;
		co2:_FillValue = -99.99f ;

// global attributes:
		:references = "Keeling_etal1996, Keeling_etal1995" ;

• An example of a variable: co2, representing averaged concentrations.
• An example of a dimension: T, representing a time axis.
• An example of a variable attribute: units, associated with the co2 variable.
• An example of a file attribute: references, which applies to the whole file.

2008 Unidata NetCDF Workshop for Developers and Data Providers > The "Classic" NetCDF Data Model