UPDATE: KEP 2: Modification of datetime: store local time, add 'tz' attribute (revision #10743)

Shawn Walker swalker at bynari.net
Wed Jan 26 20:48:38 CET 2011

On 1/26/2011 1:29 PM, Georg C. F. Greve wrote:
> On Wednesday 26 January 2011 18.46:29 Shawn Walker wrote:
>> I thought I bump this response from Joon. 
> It would be great if you could maybe look at the response to the bumped mail:
> 	http://kolab.org/pipermail/kolab-format/2011-January/001200.html
> The mapping between local time and UTC is ambiguous, as explained in the KEP. 
> So the only thing that is certain is that Outlook does not handle this 
> strictly according to UTC, even if the documentation may say that.
> The reason is that if it did, there would be no way to specify "11am every 
> Tuesday all year" in Outlook, the meeting would jump one hour at the DST 
> boundary. I don't think that is how Outlook behaves.
> So we'll need to figure out what Outlook actually does.

I created a recurring event in Outlook that is a daily recurring event at 8:00 AM.  Outlook does not
adjust the time on March 13th (I'm in Central Time Zone) since the time is supposed to be always
8:00 AM for me regardless.  I then changed my time zone to Berlin, Outlook updated the preview with
March 13th one hour back to 2:00 PM.

We are required to set the timezone definition in Outlook, the only tricky part for Outlook
developers is being able to translate a Olsen timezone information into the correct Windows timezone
information.  I'm not sure if anybody is aware of how Windows exactly does timezones internally, but
Windows timezones is backwards, but that just part of the headache that windows developers has to
put up with.

> I suspect it tries some "smart" compensation for DST, so we should figure out 
> what it actually does by feeding it a couple of recurrences with different 
> times with DST in effect or not. Could you help with that?
> Best regards,
> Georg

Shawn Walker
Senior Software Developer
swalker at bynari.net
Bynari, Inc.
222 W Las Colinas Blvd, Suite 1320N
Irving, TX  75039
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