Hi @JimBiardCics
> If you dig into the WKT string to find the axes, shouldn't there be a pretty
> clean mapping between the WKT axis names and the coordinate variable standard
> names? What is the particular reason why people feel that this is
> insufficient?
This is indeed the concern I am raising.
That the pretty clean mapping does not exist in many cases. Understanding
relations may require partial string matching, interpretation or inference, all
difficult to encode into software. The vocabularies within CF and within
CRS-WKT are similar but there are plenty of differences to manage, and I don't
think it is worth the effort
They also imply the parsing of the CRS-WKT to comprehend this aspect.
For example, this example of a CS for a Projected CRS is stated in the WKT-CRS
standard:
```
CS[Cartesian,2],
AXIS["(E)",east],
AXIS["(N)",north],
LENGTHUNIT[“metre”,1.0]
```
The text in the quotes is optional and not controlled.
In CF terms in this case, the coordinate variable definitions may use the
standard_name `projection_x_coordinate` and `projection_y_coordinate` but these
are optional.
Given two sets of optional strings, one of which is not a controlled
vocabulary, and implementing reference ordering based on this seems to me to be
too much of a minefield. Hence I have come to the view that explicit is better
here.
This is where the broader conversations within #222 re-triggered this topic and
motivated this activity.
I prefer to use the already in place syntax and provide clear interpretation to
enable a data producer to provide this information explicitly.
This should enable my software to be set up to simply pass coordinate values
and CRS-WKT strings to a suitable application, written by specialists, which
can provide me with all of the rich functionality that referencing by
coordinates delivers. There's minimal complication for me at this point.
I hope that this will allow us to provide a set of good practice templates to
provide to data producers to enable them to adopt.
> I want to make sure of the reason for this proposed change. This change is
> being made to provide a way for software to automatically order the
> coordinate variables correctly when handing a WKT string and coordinate
> values to a function that would do coordinate transformation. We are mapping
> variables by name to CRS axes. Is that right?
yes, this is my interpretation as well.
I hope this is helpful clarification
mark
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