[VOTE] restructure date-time value descriptions

[Tim Bergsma]

I vote approve.

In my heart, dateTime feels and works like interval.  But I have to
concede that the case for ordinal can be made.  The deciding factor for
me is that the proposed change knocks down some other weirdness, such as
having the dateTime unit type available under multiple measurement
scales.

I think the underlying problem is that the current measurment scale
typology does not adequately capture dateTime.  But it's too late to go
hunting for better typologies (alternatives do exist).  As long as
everyone puts dateTime in the same place, we should be able to find it.  

Peter has pointed out that numbers don't seem to fit under ordinal, and
that discontinuous ranges can't be represented under numericDomain. 
Both of these things bothered me, too, but I wasn't going to say
anything.

Peter has also suggested in passing that dateTime should just be it's
own (custom?) unit.  If this were earlier in the development process, I
would lobby strongly for going one step further, and making it its own
measurement scale.  It certainly deserves special handling, and having a
fifth measurement scale would abstract all the messiness of dateTime
away from the other four.  Users would be free to map it back in
wherever they wanted.  

Tim.

Matt Jones wrote:
> 
> After our long discussions about date-time values, and Tim's excellent
> treatises on that subject and units, I think we are coalescing on the
> idea that date-time values are most appropriately modeled as ordinal
> values (the deeper underlying issues with measurementScale
> notwithstanding).  Date-time values are ordered, but we seem to agree
> that one cannot do arithmetic calculations on them without parsing them
> and converting them to an interval scale such as "seconds since 1970".
> 
> I have modified the eml-attribute.xsd file (yes, again!) to reflect this
> emerging concensus.  You can see it in cvs at:
> 
> http://cvs.ecoinformatics.org/cvs/cvsweb.cgi/~checkout~/eml/eml-attribute.xsd?rev=1.93&content-type=text/plain
> 
> Using this new schema, a date-time attribute is described in eml like
> this (taken from the eml-sample.xml file):
> 
>        <attribute id="att.2">
>          <attributeName>year</attributeName>
>          <attributeLabel>year</attributeLabel>
>          <attributeDefinition>The year the data was collected
>          </attributeDefinition>
>          <storageType>gYear</storageType>
>          <measurementScale>
>            <ordinal>
>              <dateTimeDomain id="dd.2">
>                <formatString>YYYY</formatString>
>                <minimum>1944</minimum>
>              </dateTimeDomain>
>            </ordinal>
>          </measurementScale>
>        </attribute>
> 
> I would like to ask for a vote to determine this issue once and for all
> so we can release EML, especially as we were scheduled to release the
> final version of EML tomorrow!  So, here it is:
> 
> VOTE: The final release of EML should include the changes to
> representation of date-time values that were made in revision 1.93 of
> the eml-attribute.xsd file.  This includes moving date-time value
> descriptions to the ordinal measurementScale, and moving the format
> string into the DateTimeDomain description.
> 
> You should vote one of the following before the end of business Wednesday:
>     Approve: I understand and agree with the date-time change proposal
>     Neutral: I am neutral, or don't have a solution to propose
> Disapprove: I block this from occurring, and have a solution to propose
> 
> If you vote Neutral or Disapprove, it would be great to get comments
> from you as to why (e.g., if you vote neutral just because you haven't
> been following the discussion, it would be good to know that), and
> proposed alternatives.
> 
> Project member      Vote
> ---------------     ---------
> Tim Bergsma
> Chad Berkley
> David Blankman
> Matthew Brooke
> James Brunt
> Scott Chapal
> Corinna Gries
> Daniel Higgins
> Matthew Jones       approve
> Chris Jones
> Peter McCartney
> Ken Ramsey
> Mark Schildhauer
> 
> Thanks,
> Matt
> 
> --
> *******************************************************************
> Matt Jones                                    jones at nceas.ucsb.edu
> http://www.nceas.ucsb.edu/    Fax: 425-920-2439   Ph: 907-789-0496
> National Center for Ecological Analysis and Synthesis (NCEAS)
> 
> Interested in ecological informatics? http://www.ecoinformatics.org
> *******************************************************************
> 
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-- 
Tim Bergsma
LTER Information Manager
W.K. Kellogg Biological Station
Michigan State University
Hickory Corners, MI   49060
616/671-2337
tbergsma at kbs.msu.edu
http://lter.kbs.msu.edu