4.11 A Convention for Coordinates: Coordinate Variables

Coordinate Variables contain the coordinate values for a dimension.

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.