content, format, ctype, or xtype ?

[Mark Taylor]

On Fri, 15 May 2009, Francois Ochsenbein wrote:

> Short summary of options:
> -------------------------
> 
> (a) Date-time, timestamp, ...
>     (a0) Restrict the expression of time to JD or MJD or ... number
>     (a1) Create a new attribute (which name ? which content?)
>          =M2 (Mark's option#2)
>     (a2) Create a new datatype (equivalent to 'char' as far as the
>              data storage is concerned, with an arraysize reflecting
> 	     the accuracy, i.e. '19' for full date YYYY-MM-DDThh:mm:ss)
>          =M1 (Mark's option#1) [
>     (a3) Use a utype related to the STC data model
>              (e.g. utype='stc:AstroCoords.Time.TimeInstant.ISOTime')
>          =M4 (Mark's option#4)
>     (a4) Use a UCD (e.g. ucd='time.iso8601'; could be secondary
>              e.g.  ucd='time.release;time.iso8601')
>     (a5) Use a special unit (e.g. unit='"iso8601"')
> 	 =M3 (Mark's option#3)
>     (a6) No, use STC-S string (e.g. 'Time TT GEOCENTER 2009-05-13T19:09:30')
>              [from Arnold] 
> 
> It seems difficult to derive a strong answer from the various
> messages posted, but the impression I have after reading your
> messages is that:
>   (a4) (ucd) is among the favorite solutions, provided it does 
>        not hurt the Semantics group; 
>   (a1) (new datatype) looks attractive [but conflict between
>         model and low-level data container?] 
>   (a5) could be accomodated (except Arnold?) [and after all, 
>        'iso8601' has something to deal 'time' unit].
>   (a1) strangely nobody seems to favor a new attribute...

thank you Francois for the summary of the summaries.
For the record I would be happy with, in descending order of
preference, a1, a5, a4.  Since nobody else seems keen on a1
however it should probably be dropped.  I forsee problems with
use and adoption for the other options - I'll omit the arguments
for and against here as many of them have already been aired by 
myself and others, but I can go over them on request.

-- 
Mark Taylor   Astronomical Programmer   Physics, Bristol University, UK
m.b.taylor at bris.ac.uk +44-117-928-8776 http://www.star.bris.ac.uk/~mbt/