I think #1 is a great idea as it has been a practice in a number of satellite 
missions.

#2 I am not too fond of.  Best practice says that when offset is not specified 
implicitly GMT must be assumed. So I think specifying a ā€˜Zā€™ in ISO time stamp 
is only necessary when specifying a non zero offset.

From: CF-metadata 
<cf-metadata-boun...@cgd.ucar.edu<mailto:cf-metadata-boun...@cgd.ucar.edu>> on 
behalf of Chris Barker <chris.bar...@noaa.gov<mailto:chris.bar...@noaa.gov>>
Date: Thursday, September 22, 2016 at 8:45 AM
To: Jonathan Gregory 
<j.m.greg...@reading.ac.uk<mailto:j.m.greg...@reading.ac.uk>>
Cc: "cf-metadata@cgd.ucar.edu<mailto:cf-metadata@cgd.ucar.edu>" 
<cf-metadata@cgd.ucar.edu<mailto:cf-metadata@cgd.ucar.edu>>
Subject: Re: [CF-metadata] Temporal nitpicks. Was: CF-metadata Digest, Vol 161, 
Issue 3

On Thu, Sep 22, 2016 at 5:53 AM, Jonathan Gregory 
<j.m.greg...@reading.ac.uk<mailto:j.m.greg...@reading.ac.uk>> wrote:
Dear Chris et al.

I may have missed it - are you proposing a change or a clarification to the
text of the CF standard document?

yes and no:

Yes, in that I'm proposing that somthing be chaged in the docuemnt -- really 
about recommendations and example,s rather than chanign anything about what it 
allowed.

No, in that I (or anyone else) has not proposed any particular text.

But if there seems to be a consensus that it would be good ti updated the docs 
to make these recommendaiont,s than hopefully someone will suggest actual text. 
(I'm short of roundtoits at the moment).

I think these are the ideas:

1) recommend ISO-8601 compliant time strings

2) recommend that an offset (or 'Z') always be provided in a time string.

3) Have all examples conform to the above.

Does anyone this these are NOT good ideas?


NOTE: as I understand it, ISO-8601 time strings are acceptable to UDUnits, and 
thus this would not be a change to the standard in any way -- simply 
recommendations of good practice.

TBD: According to wikipedia, ISO requires a "T" in between teh date and time, 
but then says " It is permitted to omit the 'T' character by mutual agreement" 
so do we want to recommend one or the other? I think UDUnits does not use a T 
but maybe it will accept it. (the Python netcdf4 lib added support for the 
optional "T" a couple years ago -- no idea about any other parsing libs.


-CHB



Best wishes and thanks

Jonathan

----- Forwarded message from Chris Barker 
<chris.bar...@noaa.gov<mailto:chris.bar...@noaa.gov>> -----

> Date: Wed, 21 Sep 2016 12:52:48 -0700
> From: Chris Barker <chris.bar...@noaa.gov<mailto:chris.bar...@noaa.gov>>
> To: Nan Galbraith <ngalbra...@whoi.edu<mailto:ngalbra...@whoi.edu>>
> CC: "cf-metadata@cgd.ucar.edu<mailto:cf-metadata@cgd.ucar.edu>" 
> <cf-metadata@cgd.ucar.edu<mailto:cf-metadata@cgd.ucar.edu>>
> Subject: Re: [CF-metadata] Temporal nitpicks. Was: CF-metadata Digest, Vol
>       161, Issue 3
>
> On Tue, Sep 20, 2016 at 5:45 AM, Nan Galbraith 
> <ngalbra...@whoi.edu<mailto:ngalbra...@whoi.edu>> wrote:
>
> > Can we recommend the use of ISO-compatible date strings, with
> > the caveat that time zone should always be included?
> >
>
> Yes, we really should do that (though it's an offset that is specified, not
> a time zone)
>
> It's unfortunate that ISO defaults to local  time, and that seems to be
> > non-negotiable.
> >
>
> yup :-(
>
> This is what we use in the OceanSITES implementation of CF. Obviously,
> > it won't solve everyone's needs,
>
>
> I'm trying to see whos needs it wouldn't suit folks may well want local
> time, rather than UTC, but having it be unspecified does no one any good.
>
> and specifying times in "true" local time, with DST baked in is simply a
> nightmare for everyone --- it really, really should be discouraged!
>
> -CHB
>
>
> --
>
> Christopher Barker, Ph.D.
> Oceanographer
>
> Emergency Response Division
> NOAA/NOS/OR&R            (206) 526-6959<tel:%28206%29%20526-6959>   voice
> 7600 Sand Point Way NE   (206) 526-6329<tel:%28206%29%20526-6329>   fax
> Seattle, WA  98115       (206) 526-6317<tel:%28206%29%20526-6317>   main 
> reception
>
> chris.bar...@noaa.gov<mailto:chris.bar...@noaa.gov>

> _______________________________________________
> CF-metadata mailing list
> CF-metadata@cgd.ucar.edu<mailto:CF-metadata@cgd.ucar.edu>
> http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata


----- End forwarded message -----
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--

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.bar...@noaa.gov<mailto:chris.bar...@noaa.gov>
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