[DALI] timestamp format

[Steve Allen]

On Wed 2013-11-06T11:53:25 -0800, Patrick Dowler hath writ:
> The choices are:
>
> - do not use the Z and refer to FITS and/or STC, in whch case the
> document should not mention ISO8601 at all, or at least very
> carefully)
>
> - use the Z and refer directly to ISO8601, which Dave argued is the
> least surprising to the periphery and outside the IVOA but
> incompatible with current practice in astronomy
>
> To Z or not to Z...

The tzdata/tzcode (zoneinfo) remains constantly in flux and cannot be
guaranteed to be correct on legacy systems.  For reasons like this we
find that we must run some machines with the default timezone set to
UTC, and on other machines the applications which need to avoid those
issues explicitly set their timezone to UTC for the scope of the
application.

If I recall correctly the discussions leading to the FITS Y2K
agreement explicitly wanted to prevent the complexities of
timezone interpretation from entering the FITS standard.
The first choice is the one that was made, specifically noting
that it is only a subset of ISO8601.

--
Steve Allen                 <sla at ucolick.org>                WGS-84 (GPS)
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