In order to address time zone changes, this tool will help adjust calendar items in Outlook after the operating system has been updated with new time zone definitions. While this tool is being released in advance of the U.S. Daylight saving time rules change in 2007, it can be used for general adjustments of calendar items based on changes in time zone definitions saved in Windows or by the user making a permanent move to another time zone.
--In existing recurring appointments, Outlook has encoded the current DST rules: Instances of recurring appointments that occur during the delta period will appear one hour earlier than they should.
--For existing single-instance appointments and reminders, Outlook already calculated the universal time coordinate (UTC) value upon appointment creation: If a user creates an appointment while Windows is configured for the old DST rules and the appointment itself occurs during the "new" DST weeks, the appointment will appear one hour earlier than it should.
--Existing all-day events are associated with 24 specific hours instead of a given date: For the reasons described above, all-day events will appear to shift and thus span two days during the "new" DST weeks.
Note: Microsoft Office Outlook 2007 can automatically detect the DST change and prompt the process that updates a persons calendar to comply with the new daylight saving time rules. However, the Time Zone Data Update Tool contains enhancements that improve what is available in Outlook 2007 and should be run instead of the out-of-the-box Outlook 2007 experience.