Please see my comment below...
On 2014-04-25 7:13 AM, Nan Galbraith wrote:
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#113: Review of CF feature types
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Reporter: mgschultz | Owner: cf-conventions@…
Type: | Status: new
enhancement | Milestone:
Priority: medium | Version:
Component: cf- | Keywords: featureType, Grid, Point,
conventions | TimeSeries, Profile
Resolution: |
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Comment (by ngalbraith):
With regards to item 1, I'm not sure I see a contradiction between stating
that "space-time coordinates ...are mandatory" and "If there is only a
single feature to be stored in a data variable, there is no need for an
instance dimension." I do agree that the instance variable should be shown
as an optional field in the table.
Please distinguish between instance dimension and instance variable.
Note that the CF standard says "there is no need for an instance
*dimension*." It does not say there is no need for an instance
*variable* (which may be a scalar if there is only one instance in the
file and no instance dimension).
If the instance *variable* is not present, there will be no variable to
have the cf_role metadata (e.g., cf_role = trajectory_id) and the file
will not be CF DSG compliant. Similarly, if the instance variable is not
present, there is no way for software to aggregate a collection of
instances.
My question on this is whether, in the absence of an instance variable,
the featureType attribute still should be used, and, if not, whether such
a file is CF1.6 compliant. This probably has been answered somewhere in
the email discussion, but should be clarified in the docs.
On item 2, I'm glad you're referring to the Java source; I just did a
quick search on my email archive, looking for feature type in subject
lines, and find this cropping up in the netcdf-java and thredds lists as
well as in cf-metadata.
I have one additional item that's been in 4 or 5 email threads, on which I
admit to having dropped the ball every time. It's the question of
describing 2D data from surface moorings as timeSeriesProfile features. Is
this within the scope of this ticket? I'm sure it's a closed issue for
most CF folks, but I have lingering questions; don't want to divert the
effort going on here, though.
Thanks - Nan
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--
Sincerely,
Bob Simons
IT Specialist
Environmental Research Division
NOAA Southwest Fisheries Science Center
1352 Lighthouse Ave
Pacific Grove, CA 93950-2079
Phone: (831)658-3205
Fax: (831)648-8440
Email: [email protected]
The contents of this message are mine personally and
do not necessarily reflect any position of the
Government or the National Oceanic and Atmospheric
Administration.
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