[Ietf-calsify] RRULEs, TimeZones

[Cyrus Daboo]

Hi Mark,

--On Wednesday, October 13, 2004 2:47 PM -0400 Mark Swanson 
<mark at scheduleworld.com> wrote:

>> Of course, but the presentation layer needs to know that the event was
>> created in (and is intended for) "Candian/Eastern" time.
>
> Perhaps "(and is intended for)" is also a key factor. F.E. I assume that
> someone flying to Vancouver for a meeting would ask his presentation
> layer to  display his events for that day in the Pacific timezone. I
> believe this to be  logical.

The timezone needed for 'presentation' may well be different than the 
timezone needed when editing an event. Consider: I am in EST timezone but 
want to schedule an event for a meeting next week on the west coast in PST 
- so I create the event and set the start to 12:00 pm PST - note that I 
edit it in PST not my current 'presentation' timezone of EST. If at some 
later point I want to edit it, the edit dialog should show the time in PST 
- not the current 'presentation' timezone, whatever that may be.

Thus timezone information does need to be included with event data - 
however that info only needs to be a 'hint' - the actual time can be stored 
in UTC.

Hence my earlier suggestion of having a 'TZHINT' parameter on times 
specified in UTC. That 'hint' is only needed is special circumstances, e.g. 
editing, rrule expansion - all other operations can be done with the UTC 
time without reference to it.

-- 
Cyrus Daboo