Subject: [Ietf-calsify] RRULEs with DTSTART and DTEND in different time zones

From: lennox at cs.columbia.edu (Jonathan Lennox)
Date: Tue Nov 7 08:45:12 2006

People have mentioned that the case needs to be handled when DTSTART and
DTEND are in different time zones -- for example, for plane flights.

Have people thought about what this means for recurrence durations, when the
two time zones have varying relative UTC offsets?

Specifically:

   DTSTART;TZID=America/Phoenix:20061027T150000
   DTEND;TZID=America/Los_Angeles:20061027T160000
   RRULE:FREQ=WEEKLY;COUNT=2

The first instance of the recurrence starts at 2006-10-27 15:00:00 MST (GMT+7), and
ends at 2006-10-27 16:00:00 PDT (GMT+7), 1 hour later.

The second instance of the recurrence starts at 2006-11-03 15:00:00 MST
(GMT+7), and ends -- when?  One could argue for either 2006-11-03 15:00:00
PST (GMT+8), 1 hour later, or 2006-11-03 16:00:00 PST (GMT+8), 2 hours
later.

Does anyone handle this case?  If UIs allow separate timezones for event
starting and ending times, this actually seems like something that could
poentially be constructed in a calendar UI.

-- 
Jonathan Lennox
[email-masked]