[Kolab-devel] KEP 2: Modification of datetime type, introduction of 'tz' sub-tag

Jeroen van Meeuwen (Kolab Systems) vanmeeuwen at kolabsys.com
Wed Nov 24 11:49:31 CET 2010

On Wednesday, November 24, 2010 09:29:58 am Andrew McMillan wrote:
> On Tue, 2010-11-23 at 16:17 +0100, Jeroen van Meeuwen (Kolab Systems)
> wrote:
> > I'm saying that the "+0200" is a problem, because the number is
> > subject to local UTC offset changes, such as is the case with DST.
> > 
> >  There is virtually no way "+0200" can be reliably resolved to the
> > 
> > indended UTC datetime, as we have no indication of the authoritative
> > location for which the +0200 was originally intended; and thus also no
> > rules we can use on UTC offset changes.
> No, in fact +02:00 *only* describes an offset from UTC.  It *cannot*
> describe a timezone, because it does not tell us anything about the
> legislative domain responsible for changes to that offset in the past or
> the future.

I'm sorry for the misunderstanding; I was certainly not attempting to argue 
the offset was a timezone, I meant to argue the offset *does never* accurately 
translate into a timezone.

> > Hence, the proposal would introduce an Olson database location entry,
> > from which we can always calculate the intended offset; for millennia
> > to come, hopefully.
> Or for as long as DST lasts...  which many of us who have been late for
> meetings, or found ourselves arriving at work when there was nobody in
> the office, would wish to be a short time indeed :-)

Exactly ;-)

Kind regards,

Jeroen van Meeuwen

Senior Engineer, Kolab Systems AG

e: vanmeeuwen at kolabsys.com
t: +316 42 801 403
w: http://www.kolabsys.com

pgp: 9342 BF08
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