[CF-metadata] cartesian_x_coordinate

[Schmidli Juerg]

> > Would it be possible to add something like
> > cartesian_x_coordinate, cartesian_y_coordinate
> > to the standard name list.
> 
> These are too unspecific - we should indicate what kind of coordinate they are.
> What are their units? If they are in degrees, the existing standard_names
> grid_latitude and grid_longitude might be appropriate. Jonathan

For instance, meters (m) or kilometers (km).

Juerg