A variable with the same name as a dimension is called a coordinate variable. Many programs that read netCDF files recognize and use any coordinate values they find.

To be useful for defining a coordinate system, a coordinate variable:

• should be one-dimensional
• should specify the coordinate value corresponding to each dimension index
• should contain no missing values
• should have values that are strictly increasing or strictly decreasing

Examples of typical coordinate variables include lat, lon, level, and time, corresponding to dimensions with the same names.

The notion of coordinate variables has been generalized to multidimensional coordinate axes and sets of coordinate axes that comprise coordinate systems in the netCDF Java library and the Common Data Model it supports. The CF Conventions also provide a natural meaning for multidimensional auxiliary coordinate variables, identified by a coordinates attribute.

2009 Unidata NetCDF Workshop for Developers and Data Providers > The "Classic" NetCDF Data Model