[Ietf-calsify] rrule question from draft-cstoner-rfc2445bis-00

[Reinhold Kainhofer]

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On Thursday 17 November 2005 18:09, Preston Stephenson wrote:
> In section 8.3.5  Recurrence Rule, it states:
>                                                            When used
> with a recurrence rule,
>    the "DTSTART" and "DTEND" properties MUST be specified in local
> time
>    and the appropriate set of "VTIMEZONE" calendar components MUST
> be
>    included.
>
> I understand the MUST including the VTIMEZONE, but why is local time
> required. Why can't it be UTC time also?

Because Recurrence rules are highly time-zone dependent.
E.g. take an event that recurs very monday at 0:30 Central European Summer 
Time (UTC+2). If you shift the times to UTC, the event recurs at 22:30 every 
SUNDAY in UTC.

For weekly recurrences that RRULE might be adjusted to UTC, but e.g. if you 
have a recurrence every first monday of the month at 0:30 CEST, you can't 
express this in UTC any more at all (because the sunday before the first 
monday of a month is not necessarily the first sunday of the month).

Cheers,
Reinhol

- -- 
- ------------------------------------------------------------------
Reinhold Kainhofer, Vienna University of Technology, Austria
email: reinhold at kainhofer.com, http://reinhold.kainhofer.com/
 * Financial and Actuarial Mathematics, TU Wien, http://www.fam.tuwien.ac.at/
 * K Desktop Environment, http://www.kde.org, KOrganizer maintainer
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