Subject: RECUR issue: DST-change anomalies

From: John Stracke <[email-masked]>
Date: Tue, 20 Mar 2001 14:38:34 -0600

At the calsch dinner last night, we discussed what happens when
you have a recurring event scheduled for, say, 1:30 AM, when it
falls on the night of a DST change, so that 1:30 AM occurs twice
or not at all.  The sense of the table was that the code
evaluating the RECUR should be naive about it: if 1:30 AM occurs
twice, the event occurs twice; if 1:30 AM doesn't occur, the
event doesn't occur.  Otherwise, you get into trying to guess
what the user means.  The CUA, however, can note when this is
happening, and *ask* the user what they want to do, and adjust
the iCalendar with RDATE/EXDATE/EXRULE (expressing the times in
GMT to disambiguate).

The actual decision on what the evaluation code should do is less
important, but it should be consistent across implementations.
Engines should be predictable, but user-agents should be helpful.

--
/==============================================================\
|John Stracke    | http://www.ecal.com |My opinions are my own.|
|Chief Scientist |=============================================|
|eCal Corp.      |The voices say I'm not schizophrenic, but    |
[email-masked]|they're not sure about you.                  |
\==============================================================/

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From: [email-masked]
Date: Tue, 20 Mar 2001 18:47:48 -0500

John, I currently with a product (that will remain nameless for now) that 
has problems with timezones and in particular DST and change overs, in 
particular for all day events.  The product assumes a "12:00 midnight" 
timeframe for all day events.  When you are in a different timezone, it 
shows up on the calendar twice.   I work with another vendors product and 
they too have the same problem.  I think this is a bigger issue that may 
appear on the surface.  Vendors are having problems making the events span 
timezones and days in their existing products - much less us trying to 
solve this in our spec/draft.  I hope we can figure this out - because if 
we do, I need to forward it to these vendors (both quite large, by the 
way) and say - here, this is the way to make it work. 8-)
___________________
Patricia Egen Consulting
www.egenconsulting.com
423-875-2652

John Stracke <[email-masked]>
Sent by: [email-masked]
03/20/01 03:38 PM

        To:     calsch WG <[email-masked]>
        cc: 
        Subject:        RECUR issue: DST-change anomalies