[Ietf-calsify] Section 4.8.5.3 Recurrence Date/Times: RDATE < DTSTART

[Bernard Desruisseaux]

Reinhold,

In my opinion we need to allow RDATE to be less than DTSTART,
even more so now that DTSTART should be synchronized with the
recurrence rule.

Let's say I want to have a meeting today (Monday) with three
further instances on the next upcoming Tuesday. I could easily
do that with an RDATE set to today (Monday) and a DTSTART set
to tomorrow (Tuesday) and RRULE:FREQ=WEEKLY;BYDAY=TU;COUNT=3.

Cheers,
Bernard

Reinhold Kainhofer wrote:
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> Am Sonntag, 5. November 2006 23:33 schrieb Bernard Desruisseaux:
>> In section 4.8.5.3 Recurrence Date/Times of RFC 2445 it says:
>>  > The "DTSTART" property defines the first instance in the
>>  > recurrence set.
>>
>> I believe this section should clarify that the "RDATE" property
>> value can actually be earlier in time than the value of the
>> "DTSTART" property.
> 
> I always understood this sentence that the DTSTART is always the first 
> date/time of the event and RDATE cannot be earlier. Otherwise, to determine 
> whether an event happens today, one would have to look at all recurrences of 
> all events, future or past. If the DTSTART is always the first time, then it 
> suffices to look at all events that have already started at the given date 
> (i.e. DTSTART<=givenDateTime).
> 
> 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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