I’m wondering about the `string x(x)` and `char x(x,x_len)` constructs. While the [main body of the NUG is somewhat vague in its definition](https://www.unidata.ucar.edu/software/netcdf/docs/netcdf_data_set_components.html#coordinate_variables) of a “coordinate variable”, the NUG Best Practices “Coordinate Systems” [section](https://www.unidata.ucar.edu/software/netcdf/docs/BestPractices.html#bp_Coordinate-Systems) is more precise: > A **coordinate variable** is a one-dimensional variable with the same name as > a dimension, which names the coordinate values of the dimension. It must not > have any missing data (for example, no _FillValue or missing_value > attributes) and must be strictly monotonic (values increasing or decreasing). > A two-dimensional variable of type char is a **string-valued coordinate > variable** if it has the same name as its first dimension, e.g.: char time( > time, time_len); all of its strings must be unique.
Also, the first sentence of CF [Section 4. “Coordinate Types”](http://cfconventions.org/Data/cf-conventions/cf-conventions-1.8/cf-conventions.html#coordinate-types) says: > The commonest use of coordinate variables is to locate the data in space and > time, but coordinates may be provided for any other continuous geophysical > quantity (e.g. density, temperature, radiation wavelength, zenith angle of > radiance, sea surface wave frequency) or discrete category (see [Section 4.5, > "Discrete > Axis"](http://cfconventions.org/Data/cf-conventions/cf-conventions-1.8/cf-conventions.html#discrete-axis), > e.g. area type, model level number, ensemble member number) on which the > data variable depends. Which I initially interpreted to implicitly allow for String/char “coordinate variables”. Are there other locations that are more explicit about disallowing non-numeric “coordinate variables”? -- You are receiving this because you are subscribed to this thread. Reply to this email directly or view it on GitHub: https://github.com/cf-convention/cf-conventions/issues/174#issuecomment-595493657 This list forwards relevant notifications from Github. It is distinct from [email protected], although if you do nothing, a subscription to the UCAR list will result in a subscription to this list. To unsubscribe from this list only, send a message to [email protected].
