Ben,
Section 3.1 of the CF Standard says, " The|units|attribute is required
for all variables that represent dimensional quantities". Also, "Units
are not required for dimensionless quantities. A variable with no units
attribute is assumed to be dimensionless."
A string coordinate is not "dimensional", and thus a units attribute is
not required. Chapter 6 describes label coordinates (the name given to
string valued coordinates).
Grace and peace,
Jim
On 10/3/14, 10:16 AM, Ben Hetland wrote:
> On 2014-10-03, Jim Biard <jbiard at cicsnc.org> wrote:
>> The 'no units' case is covered by leaving off the units attribute.
> Wouldn't that be in violation of the CF convention?
> I was under the impression that _all_ dimensional quantities need that attribute, and a "coordinate" would by its very nature always imply a dimensional aspect, or is there something I've missed?
>
> If it were a 'dimensionless' value, using just "1" as a udunits string would work fine, but here I suppose the request is more along the lines of an _undefined_ unit (as in "missing", "unknown" or "not applicable").
>
>
>> On 10/3/14, 6:59 AM, Hedley, Mark wrote:
>> But I believe that I can create a CF auxiliary coordinate with string values without any concern.
> Perhaps you could provide some concrete examples where you think a string as such (*) may be used as a coordinate or dimension?
>
>
> -+-Ben-+-
>
> [*] i.e., the string is not just an alternative representation of some numeric value or scale, which it could have been converted into by means of a defined process.
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Received on Fri Oct 03 2014 - 08:40:30 BST
