More DST fall-out

[David Farber <dave () farber net>]

Begin forwarded message:

From: Bob Frankston <Bob19-0501 () bobf frankston com>
Date: March 11, 2007 1:11:09 PM EDT
To: Dave Farber <dave () farber net>
Subject: More DST fall-out

From http://www.microsoft.com/windowsmobile/daylightsaving/default.mspx



This is a reminder of the problem of representation. While it’s  
useful to represent all dates as a time in seconds from a base time  
that’s often very wrong. Too bad we don’t have a common  
representation that can indicate that 11AM means 11AM by the local  
clock in a given time zone. Thus if the conference call is 11AM New  
York time and I’m living Paris I will be notified appropriately even  
if I’m passing through Indiana which seems to have it’s own notion of  
DST.



Of course we have events on lunar calendars and other calendars  
though I don’t know how far we should push the representation issue.  
If we have a holiday whose rule is “use the lunar calendar except  
when another religion is using that day and then …”. Or we may have  
events on a Star Trek calendar.



But the common case of coordinating events tied to the time in a  
particular place on Earth are common enough to warrant common handing  
– being told someone’s birthday started at 23:00 the day before is  
not only silly but risks truncation errors.



After reading the suggestions below I can’t help but ask – if you  
know this why don’t you fix the programs rather than the users?



In fact, when I was at Microsoft I urged putting the time zone  
information into the CMOS along with the clock information so you run  
into another fun foible – having multiple operating systems or apps  
each trying to fix DST without knowing about the other. Or simply  
getting totally confused when flying to or from Japan.







Installation tips

·                         Rapid succession of steps is important
Run the Outlook Time Zone Update Tool on your PC as soon as possible  
after the DST update is applied to all of your PCs. If meetings  
between March 11, 2007 and April 1, 2007 are scheduled after the DST  
files are installed but before the tool is run, meetings will  
erroneously be moved one hour earlier. To correct such calendar  
items, organizers should manually update such meetings to ensure they  
are scheduled accurately for themselves and all invitees.

·                         All connected devices must be updated
Even if you correctly update your PC with the DST 2007 update, when  
you view your calendar from a non-updated mobile device running  
Windows Mobile, your meetings during the extended DST period will be  
shifted by one hour. Meetings created on your non-updated device will  
need to be updated on your PC by running the Outlook Time Zone Update  
Tool again.

·                         If some users have not updated their  
Outlook, it will affect other users
The Outlook Time Zone Update Tool only updates meetings for which the  
user is the organizer, and then automatically sends updates for those  
meetings to attendees. Meetings that you are invited to but did not  
organize will not be updated until the organizer updates the meeting  
and prompts you to change to the correct time. Additionally, meetings  
created by a delegate on your behalf from an non-updated PC will need  
to be updated on your PC by running the Outlook Time Zone Update Tool  
again.







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