[Ietf-calsify] summary of jabber sessions and confirmation of issues

[Reinhold Kainhofer]

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Am Mittwoch, 11. Oktober 2006 17:37 schrieben Sie:
> Hi Reinhold,
>
> --On October 11, 2006 5:16:28 PM +0200 Reinhold Kainhofer
>
> <reinhold at kainhofer.com> wrote:
> > DTSTART;VALUE=DATE:20061011
> > RRULE:FREQ=WEEKLY;COUNT=1;BYDAY=MO
> > RRULE:FREQ=WEEKLY;COUNT=1;BYDAY=FR
> >
> > will result in the event only happening on Oct 11, but not on any monday
> > or  any friday, which is not what I would expect. I wonder how different
> > implementations interpret this snipplet...
> > Intuitively, I would expect the event to happen on Oct 11, plus on the
> > next  one monday and on the next one friday.
>
> An instance representing the supplied DTSTART value is always present as
> per 4.8.5.4 (which says in the Description paragraph: 'The "DTSTART"
> property defines the first instance in the recurrence set.'). So a COUNT=1
> will only ever generate the DTSTART instance. So your 'intuitive'
> expectation is wrong.

On the other hand, section 4.8.5.2 about EXRULE (and section 4.8.5.1 about 
EXDATE) says that the EXRULE/EXDATE properties can be used to exlude the 
DTSTART. Notice the word *can* and "in such cases", which indicate that the 
DTSTART is not always automatically generated by an EXRULE.

So, the DTSTART is not always the first instance in the recurrence set, and an 
EXRULE does not necessarily exclude the DTSTART. Consequently, a recurrence 
rule does not necessarily generate the DTSTART as its first date/time.

Cheers,
Reinhold

- -- 
- ------------------------------------------------------------------
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
 * Chorvereinigung "Jung-Wien", http://www.jung-wien.at/
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