Dear All,
I think Chris has hit the nail on the head here. In my view neither the Standard Name nor the units of measure are the way to describe what is in essence the format of a string. So, what other options are there open to us? I can see three alternatives:
1) Use the long name to describe the string format (not just the standard used but the profile)
2) Use the existing calendar attribute
3) Specify a suitable extension to CF to do the job.
These are roughly in my order of preference.
Cheers, Roy.
________________________________________
From: CF-metadata [cf-metadata-bounces at cgd.ucar.edu] On Behalf Of Chris Barker - NOAA Federal [chris.barker at noaa.gov]
Sent: 27 March 2013 15:56
Cc: cf-metadata at cgd.ucar.edu
Subject: Re: [CF-metadata] New standard name: datetime_iso8601 (standard_name or units?)
On Wed, Mar 27, 2013 at 8:05 AM, Steve Hankin <steven.c.hankin at noaa.gov> wrote:
> ISO date-time strings are a way of encoding the physical quantity
> that we know as TIME. So TIME is the "right" standard_name for ISO
> date-time strings per the definition quoted above.
>
> Now, it may be that there is a compelling argument to violating the normal
> definition of standard_name for the case of ISO date-time strings. Or on
> the other hand is it preferable to use the units attribute to indicate the
> use of an ISO date-time string?
An ISO string for a datetime is not a name (it's still time), but it
is not a unit either.
What it is is a data type -- more akin to a float or integer -- i.e. a
particular way to translate bytes to a value. The bytes are a char
array, and the value is the datetime itself.
I don't know if thinking about it this way is helpful, as we are
building on netcdf, and I don't now that netcdf allows you to define
new data types, but food for thought.
Also, of course, all the other data types in netcdf (and CF) are
direct translations to commonly used binary formats in computers, and
this one is not.
hmm -- a quick peak at the netcdf4 docs says:
"The richer enhanced model supports user-defined types and data structures"
So maybe this could be a user defined type?
Having said that, I don't support using ISO strings to define
datetimes in CF. I understand particular use-cases, like keeping the
original time stamp from a data collection system and the like, but
then maybe it's really just arbitrary auxiliary text information, in
which case maybe we don't need a standard name or custom data types at
all.
-Chris
--
Christopher Barker, Ph.D.
Oceanographer
Emergency Response Division
NOAA/NOS/OR&R (206) 526-6959 voice
7600 Sand Point Way NE (206) 526-6329 fax
Seattle, WA 98115 (206) 526-6317 main reception
Chris.Barker at noaa.gov
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Received on Thu Mar 28 2013 - 03:48:19 GMT
