[ietf-calsify] zero-time events in rfc2445bis

Bernard Desruisseaux bernard.desruisseaux at oracle.com
Tue Jan 27 06:47:10 PST 2009

Hi Reinhold,

As it stands I don't believe there is any restriction on zero-time events.

If DTSTART is DATE-TIME value you can either omit DTEND, or set DURATION 
to zero (e.g., "P0S").

If DTSTART is a DATE value you can set DURATION to zero (e.g., "P0D").

That being said, I don't know why RFC2445 had a restriction on DTEND 
being required to be later in time than DTSTART...


Reinhold Kainhofer wrote:
> Hash: SHA1
> Hi all,
> In RFC2445bis, is it possible to have zero-time events or not? In particular, 
> the section "  Date/Time End" says that the DTEND MUST be later in 
> time than the DTSTART, so zero-time events are not possible using DTEND.
> On the other side, "3.6.1.  Event Component" says: 
> "For cases where a "VEVENT" calendar component
>       specifies a "DTSTART" property with a DATE value type but no
>       "DTEND" nor "DURATION" property, the event's duration is taken to
>       be one day.  For cases where a "VEVENT" calendar component
>       specifies a "DTSTART" property with a DATE-TIME value type but no
>       "DTEND" property, the event ends on the same calendar date and
>       time of day specified by the "DTSTART" property."
> So, it seems that to get a zero-time event, one MUST leave out the DTEND and 
> the event must have a time assigned. For events with DTSTART being a DATE-TIME 
> the default length is zero, while for events with DTSTART being a DATE the 
> default length is one whole day. Isn't this inconsistent?
> Cheers,
> Reinhold
> - -- 
> - ------------------------------------------------------------------
> Reinhold Kainhofer, reinhold at kainhofer.com, http://reinhold.kainhofer.com/
>  * Financial & Actuarial Math., Vienna Univ. of Technology, Austria
>  * http://www.fam.tuwien.ac.at/, DVR: 0005886
>  * LilyPond, Music typesetting, http://www.lilypond.org
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