Dear all
CF has always disallowed non-numeric coordinate variables (to the best of my 
knowledge) so, as Martin says, no change is proposed in that respect. The 
position of the NUG is different perhaps because it doesn't have auxiliary 
coordinate variables. CF has string-valued auxiliary coordinate variables, as 
we all agree, and they should not have the name of (any of) their dimensions. 
Things could be done other ways, but I believe that's how they are in CF at 
present. Is there a reason why it needs to be changed, arising from use-cases?
I think the essential distinction between a dimension coordinate variable and 
an auxiliary coordinate variable is that the former is inherently ordered by 
its coordinate values, while the latter is an unordered collection (which is 
given an order only by the dimension coordinate variable, if there is one). Of 
course you can choose to order an auxiliary coordinate variable by its values 
(if there is no dimension coordinate variable) or in any way you choose, but 
the order is not an inherent part of the metadata it conveys.
Best wishes
Jonathan

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