Dear Richard
That's right. No change since 1.0 has so far passed beyond being "provisional"
since we didn't definitely agree how to do that. I am not strongly in favour of
provisional status myself, but others have argued strongly for it previously.
I think there is a good argument that we should try hard to avoid making a
mistake which we have to reverse, because data lasts forever, and if data were
written with a flawed standard, it would forever be a nuisance. Of course in
principle this can be detected and perhaps worked round using the version from
the Conventions attribute, but in practice I suspect this attribute is not
normally written scrupulously correctly, nor inspected by analysis software.
So we should be careful, and that means a "cooling-off" period during which
data is at risk of being invalidated if it uses a provisional convention is a
reasonable safeguard, but it should not be a long period - months, not years,
I would say.
Best wishes
Jonathan
----- Forwarded message from "Hattersley, Richard" <richard.hattersley at metoffice.gov.uk> -----
> Date: Tue, 18 Mar 2014 09:05:36 +0000
> From: "Hattersley, Richard" <richard.hattersley at metoffice.gov.uk>
> To: "Gregory, Jonathan" <j.m.gregory at reading.ac.uk>,
> "cf-metadata at cgd.ucar.edu" <cf-metadata at cgd.ucar.edu>
> Subject: RE: [CF-metadata] Editing/publishing workflow
>
> > I'd like to propose changing the rules. That's something the conventions committee can agree, I believe. I would suggest the simplest possibility, if we wish to retain provisional status, is to specify a time. We could say that, after one year from acceptance or when the next version of the conventions document is published, whichever is later, a change becomes permanent. What do you think?
>
> The more I consider the concept of "provisional status" the more it concerns me. What does it actually mean for a netCDF file to use a particular "Conventions" attribute value? How can one tell what is still in provisional status? What version should data writers be using? I've checked back through 1.3, 1.4, 1.5, and 1.6 and they all still contain sections marked as provisional. Using the analogy to software versions that has been raised elsewhere, the CF convention versions are essentially pre-release versions, e.g. 1.6-beta, and are not suitable for production use.
>
> I would argue that the simplest possibility is to drop the "provisional status" concept. Identifying and resolving problems should happen during the discussion of the modification and its subsequent application to the conventions document.
>
> If a further flaw, ambiguity, etc. is subsequently discovered prior to the publication of the next version of the conventions then it can easily be resolved at that time.
>
> If a problem is discovered after the publication of the next version then a correction must be applied and published in a *new* version. That version could be a "bug fix" version (e.g. 1.6.1) or it could just wait for the next normal release, e.g. 1.7. It would help to agree that process in advance but I have no strong opinion either way.
>
>
> Richard Hattersley
> Expert Software Developer
> Met Office FitzRoy Road Exeter Devon EX1 3PB United Kingdom
> Tel: +44 (0)1392 885702
> Email: richard.hattersley at metoffice.gov.uk Web: www.metoffice.gov.uk
>
> -----Original Message-----
> From: CF-metadata [mailto:cf-metadata-bounces at cgd.ucar.edu] On Behalf Of Jonathan Gregory
> Sent: 13 March 2014 17:24
> To: cf-metadata at cgd.ucar.edu
> Subject: Re: [CF-metadata] Editing/publishing workflow
>
> Dear Jeff
>
> > Present CF Conventions policies require that all changes be
> > provisional, and marked as such in the document, until determined to
> > be permanent at a later time (this determination has never been made).
> > That's the meaning of all the pink and yellow highlighting in the
> > document at cf-pcmdi.llnl.gov.
>
> Yes, this is a issue. As Richard said, it doesn't matter how it is marked. The problem is that all changes, however old, are still marked as provisional, as you said. This is (a) a bit silly and (b) a nuisance as regards legibility of the doc. The aim of provisional status was to allow time for people to try out the change, in case a logical flaw was discovered which hadn't been fore- seen at the time of the proposal. This was because of the concern that many or most proposals concern data which has not yet been written, so the metadata being proposed can't have been thoroughly tested. It was supposed that some tests, using specified software, would be used to demonstrate the new feature was "working", but no-one had time to work out the details for this.
>
> I'd like to propose changing the rules. That's something the conventions committee can agree, I believe. I would suggest the simplest possibility, if we wish to retain provisional status, is to specify a time. We could say that, after one year from acceptance or when the next version of the conventions document is published, whichever is later, a change becomes permanent. What do you think?
>
> Cheers
>
> Jonathan
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----- End forwarded message -----
Received on Tue Mar 18 2014 - 05:09:11 GMT
