[Cube/vo-dml] ivoa datatypes

[Arnold Rots]

The time issue is a little more complicated than that.
Assuming that the datetime primitive type is a subset of ISO-8601,
TimeValue is really an ISOTimeInstant.
One should be cognizant of the fact that time instants can be expressed
through an ISO-8601 datetime string, JD, or MJD; they are fully equivalent
and equally valid expressions - except for the fact that ISO-8601 has a
limited range.
Units do not really play a role here: ISO-8601 has no units and 'd' is
implied
fro JD and MJD.
However, TimeInstant should be clearly distinguished from TimeDuration
which does require a unit (s, d, a, cy, yr).

  - Arnold

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Arnold H. Rots                                          Chandra X-ray
Science Center
Smithsonian Astrophysical Observatory                   tel:  +1 617 496
7701
60 Garden Street, MS 67                                      fax:  +1 617
495 7356
Cambridge, MA 02138
arots at cfa.harvard.edu
USA
http://hea-www.harvard.edu/~arots/
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On Thu, Apr 24, 2014 at 1:33 PM, CresitelloDittmar, Mark <
mdittmar at cfa.harvard.edu> wrote:

>
> A little background:
>   For the cube model work, I have baselined all the related models to a
> common set of base datatypes.  I selected the 'ivoa types' model from
> vo-dml in order to facilitate efforts to represent these models in that
> framework.
>    The current description is here:
>
> https://volute.googlecode.com/svn/trunk/projects/dm/vo-dml/models/ivoa/IVOA.png
>
>
> Request:
>   During this effort, there are a couple types that I would like to add to
> this suite.
>   1) TimeValue: extends AtomicValue
>         + value: datetime     # ivoa:datetime primitive type
>         + unit: Unit              # ivoa:unit primitive type.
>
>       This could be under Quantity (TimeQuantity) or separate since I
> expect the 'units' attribute
>       would be more restrictive than the generic Unit... to just the time
> domain.
>
>    2) URL
>        I would prefer to have a type for URL distinct from anyURI, to make
> the distinction more clear in the models (rather than relying on qualifying
> text).
>
>     3)  in STCMod, I also have 'Vector' extending AtomicValue.. but since
> this contains 2+ AtomicValue(s), I'm thinking this is not valid, and I will
> work on a different approach.
>
> Mark
>
>
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