Subject: [Ietf-calsify] Section 4.8.6.3 Trigger: Trigger relative to DATE value type

From: bernard.desruisseaux at oracle.com (Bernard Desruisseaux)
Date: Mon Sep 25 11:17:30 2006

In section 4.8.6.3 Trigger of RFC 2445 it says:

 > Alarms specified in an event or to-do which is defined in terms of a
 > DATE value type will be triggered relative to 00:00:00 UTC on the
 > specified date. For example, if "DTSTART:19980205, then the duration
 > trigger will be relative to19980205T000000Z.

In my opinion, applications should trigger the alarm relative to
00:00:00 of the time zone configured on the calendar that contains
the event or to-do, or the current user's preferred time zone. UTC
should only be used when no specific time zone can be found in the
current context.

Cheers,
Bernard

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From: lear at cisco.com (Eliot Lear)
Date: Mon Sep 25 11:47:48 2006

Bernard,
> should only be used when no specific time zone can be found in the

I agree in principle.  However, I am concerned about existing
implementations.  Alarms are used, and if we make this change then how
many implementations immediately become non-compliant?

Eliot

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From: reinhold at kainhofer.com (Reinhold Kainhofer)
Date: Mon Sep 25 13:29:15 2006

> many implementations immediately become non-compliant?

On the other hand, how many implementations violated the RFC so far and would 
be compliant after the change?

Cheers,
Reinhold

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From: bernard.desruisseaux at oracle.com (Bernard Desruisseaux)
Date: Tue Sep 26 08:42:58 2006

Hi Eliot,

> many implementations immediately become non-compliant?

The only thing that matter is whether users will receive their alarm at
the time they expect to receive them. People using applications that
implement what the RFC says will most likely not get their alarm at the
time they expect. In my case, I would receive them 5 hours in advance
during Eastern Standard Time, and 4 hours in advance when in Eastern
Daylight Time. I doubt there's any implementation that do this.

Currently, the text doesn't specify any clear requirement level (i.e.,
MAY, SHOULD, MUST). I think it should.

Thanks,
Bernard

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From: lists at block-online.eu (Oliver Block)
Date: Tue Sep 26 12:29:46 2006

> >> should only be used when no specific time zone can be found in the

In my view every application is free to do that. It would just not define the 
value for DTSTART as DATE but as DATE-TIME.
In other words: I find your opinion more intuitive than the standard and 
that's what a user will expect. On the other hand the standard will assure 
that every application will interpret a DATE value in the same way. 

Regards,

Oliver 

-- 
Leben ist mehr als ...
http://www.nak-nrw.de/p_6_4.html

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From: bernard.desruisseaux at oracle.com (Bernard Desruisseaux)
Date: Wed Sep 27 12:40:32 2006

Oliver,

Isn't the purpose of the DATE value type to allow its value to be
interpreted differently by different people depending on their time
zone? Else, why would iCalendar bother defining this value type? :-)

The exact start and end time of events such as "Christmas",
"New Year's Day", "Canada Day" etc. depends on the time zone
of the user.

Cheers,
Bernard