DALI 1.1 working draft available

[Patrick Dowler]

IIRC the UTC restriction is also inherited from VOResource

On 19 February 2016 at 10:45, Arnold Rots <arots at cfa.harvard.edu> wrote:

> UTC may be a DALI restriction, but time zones are specifically outlawed,
> both in FITS and in STC.
> On an earlier comment, decimal years can simply be specified with
> unit='a'; but they would require an indication 'B' or 'J'.
>
>   - Arnold
>
>
> -------------------------------------------------------------------------------------------------------------
> 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/
>
> --------------------------------------------------------------------------------------------------------------
>
>
> On Fri, Feb 19, 2016 at 12:30 PM, Patrick Dowler <pdowler.cadc at gmail.com>
> wrote:
>
>> As has been discussed numerous times (!) in the past, JD and MJD are
>> *not* types. For MJD values (eg Obscore t_min and t_max) one uses
>> datatype="double" unit="d" and describes the coordinate system metadata
>> using STC as Markus has described in a Note. The xtype attribute is to tell
>> consumers of the votable that the value can be further parsed to turn it
>> into a structure of some type, not further interpretted to mean something.
>> I think that is an important distinction that is often ignored
>>
>> I'm not sure about the high precision "days" + "seconds" double array.
>> You need that in TAP only if you actually want to expose a single column
>> with the multiple values, but I don't know off hand if anyone does that. (I
>> will admit to having some double array vaulued columns in our TAP service;
>> they are in a view called caom2.SIAv1 to support the coupleof columns in
>> the SIAv1 output that are arrays... but they don't have xtypes).
>>
>> Finally, the restriction of timestamps to a specific ISO8601 in UTC and
>> without timezone comes from upstream of DALI -- VOResource iirc. It has
>> been th accepted standard for years and DALI is only formalising some
>> technical bit of it for usage in services like TAP, SIA2, etc
>>
>> Emphasis: xtype tells the consumer how to further parse the value.
>>
>>
>> --
>> Patrick Dowler
>> Canadian Astronomy Data Centre
>> Victoria, BC, Canada
>>
>
>


-- 
Patrick Dowler
Canadian Astronomy Data Centre
Victoria, BC, Canada
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