Re: 2017-03-06- UTC, TImeZone, DayLight Saving Shifts, Enconding

Hi Joe,

--On March 18, 2017 at 8:01:06 AM -0700 Joe Touch <touch@isi.edu> wrote:

>     - dates MAY use local time (UTC offset by the local time zone) for
> applications that need to optimize for interacting with users

Again I want to emphasize the calendaring and scheduling perspective on 
this: because events may occur in the future, the calendaring system will 
usually store the tuple of (local date-time, time zone id). That way any 
changes to the time zone (e.g. DST rules) that occur prior to the date will 
be properly taken into account. Also, if the event is recurring, the usual 
expectation for users is that the local time remains the same even when the 
DST (or even base time zone offset) changes.

Now, I am not sure whether your document should delve too deeply into the 
calendaring and scheduling use case, but if it does then I strongly suggest 
you cross-post discussion to the calsify mailing list to get feedback from 
the c&s experts there.

On the other hand, it may be sufficient to include a statement along the 
lines of what I outlined above with a reference to a suitable c&s spec. In 
fact, the Calendaring and Scheduling Consortium (CalConnect) has been 
putting together a developer's guide which will include discussion on 
recurrences, time zones, date/time formats etc: 
<http://devguide.calconnect.org>, so maybe a reference to that would also 
be appropriate.

-- 
Cyrus Daboo

Received on Saturday, 18 March 2017 17:42:31 UTC