Re: [caldav] All Day Events

Cyrus Daboo <cyrus@daboo.name> Wed, 09 March 2011 02:30 UTC

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Date: Tue, 08 Mar 2011 21:31:34 -0500
From: Cyrus Daboo <cyrus@daboo.name>
To: Michael Rasmussen <mir@datanom.net>, caldav@ietf.org
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Subject: Re: [caldav] All Day Events
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Hi Michael,

--On March 9, 2011 3:21:45 AM +0100 Michael Rasmussen <mir@datanom.net>; 
wrote:

> The current situation seems to be split between two idioms. An all-day
> event of 2011-03-03 is expressed in either of these two ways:
> 1)
> DTSTART;VALUE=DATE:20110303
> DTEND;VALUE=DATE:20110303
> 2)
> DTSTART;VALUE=DATE:20110303
> DTEND;VALUE=DATE:20110304
>
> Personally I tend to vote for option 1) since option 2) clashes with
> the possibility of specifying a two day event.

The behavior specified by iCalendar is that the DTSTART is "inclusive" and 
the DTEND is "exclusive". What that means is an event ends at the very 
instant before the DTEND value. So strictly speaking your #1 example is 
wrong as it specifies an event of zero duration (it ends at the very 
instant that it starts). #2 is valid. There is a third option which is to 
just specify the DTSTART value as iCalendar states that the default 
duration in that case is one day. The fourth option is to use DTSTART and 
DURATION which is arguably the least confusing representation.

-- 
Cyrus Daboo