posted on Tuesday, February 13, 2007 8:45 AM

Exchange Daylight Savings Time (DST) Issues

by k8scott
The following information provides details about current Daylight Savings Time changes that affect CITES Exchange Services.

Background
In July 2005, Congress passed the U.S. Energy Policy Act, extending Daylight Saving Time (DST) - starting in 2007 - by approximately four weeks. As a result, DST will start three weeks earlier than previously observed on March 11, 2007, and end one week later on November 4, 2007.  

Problem
The extension of Daylight Savings Time may cause Microsoft Outlook calendar items to report incorrect time for meetings scheduled between March 11, 2007, to April 1, 2007, and from October 28, 2007, to November 4, 2007.

Microsoft released an OS patch on 12/12/2006 to fix DST issues on desktops and servers; however, items created before an OS is patched with the DST fix will be one hour late, during the extended DST periods.  

Resolution
The Exchange Services team recommends applying the OS DST patch to all devices to prevent any further meetings from being created with incorrect times.  
      
To correct items created before an OS is patched Microsoft has released a Time Zone Data Update tool. This tool moves calendar items back one hour during the extended DST periods. The drawback of this tool is that all calendar items during the extended DST periods are moved by default. If you have both correct and incorrect calendar items during these periods and you use the tool, it’s necessary to uncheck the correct calendar items in the tool so the proper time isn’t changed. Because the tool is not fail-safe, Microsoft also recommends manually editing the incorrect calendar items.

To lessen confusion and ease transition, the Exchange Services team recommends that all Exchange subscribers review meetings scheduled during the extended DST periods and manually verify times for those meetings.

Unaffected items
Calendar items that do not occur during the extended DST periods are correct and need no change. Calendar items that occur during the extended DST periods and were created with a patched OS are correct and need no change.

For further information, visit http://support.microsoft.com/kb/931667/en-us.   

If you have questions, please contact the Exchange team at exchange@uiuc.edu.