Microsoft KB Archive/934800

= Information about how daylight saving time changes in 2007 affect time stamps in Groove Virtual Office 3.x and in earlier versions of Groove =

Article ID: 934800

Article Last Modified on 8/8/2007

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APPLIES TO


 * Groove Virtual Office 3.1 Professional Edition
 * Groove Virtual Office 3.1 File Sharing Edition
 * Groove Virtual Office 3.1 Project Edition
 * Groove Virtual Office 3.1 Trial Edition
 * Groove Virtual Office 3.0 Professional Edition
 * Groove Virtual Office 3.0 File Sharing Edition
 * Groove Virtual Office 3.0 Project Edition
 * Groove Virtual Office 3.0 Trial Edition
 * Groove Workspace 2.5 Professional Edition
 * Groove Workspace 2.5 Standard Edition
 * Groove Workspace 2.5 Preview Edition
 * Groove Workspace 2.5 Project Edition

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SUMMARY
This article contains information about how Groove Virtual Office 3.x and earlier versions of Groove store and calculate time stamps. In these versions of Groove, times may be displayed incorrectly in certain items during the extended daylight saving time (DST) periods that start in March 2007. This issue affects any Groove tool that automatically generates and displays a time stamp for new items or for modified items. These items include instant messages, chat entries, Discussion tool entries, and Forms tool records. This issue does not affect the Files tool.



INTRODUCTION
The Energy Policy Act of 2005 lengthened the time period for DST in the United States beginning in 2007. In 2007 and in later years, DST begins three weeks earlier and ends one week later in the United States and in Canada. In 2007, DST begins on March 11 and ends on November 4. Additional countries and regions around the world have also made changes in their DST rules. For Groove users in different time zones, these DST changes may create time differences in any workspace tool that has data entries that display times.

This condition applies to entries that have dates and times that are entered by the user, such as Calendar events or meetings in the Meetings tool. This condition also applies to entries that automatically generate a time stamp, such as topics in the Discussion tool, in instant messages, or in chat entries. This condition does not apply to the Files tool. The File tool uses a Microsoft Windows mechanism to process time stamps.

How DST changes in 2007 affect time stamps in Groove Virtual Office 3.x and in earlier versions of Groove
Tools, instant messages, invitations, and chats in Groove Virtual Office 3.x and in earlier versions of Groove may store incorrect time stamps for dates and times in the extended DST period. Additionally, these versions of Groove may incorrectly display time stamps that were saved correctly. Time stamps are saved correctly in any one of the following situations:
 * Groove Virtual Office 3.x or an earlier version of Groove is running on a computer that is outside an affected time zone.
 * Microsoft Office Groove 2007 is running on one of the following operating systems:
 * A Windows Vista-based computer
 * A Microsoft Windows XP-based computer that is updated to accommodate the new DST rules
 * A Microsoft Windows Server 2003-based computer that is updated to accommodate the new DST rules

For more information about how to update Windows operating systems to accommodate the new DST rules, click the following article number to view the article in the Microsoft Knowledge Base:

933360 August 2007 cumulative time zone update for Microsoft Windows operating systems

These issues occur if one of the following conditions is true:
 * Groove Virtual Office 3.x or an earlier version of Groove is running on a computer that is set to an affected time zone.
 * Groove Virtual Office 3.x or an earlier version of Groove communicates with a computer that is in an affected time zone.

These issues occur because of how Groove Virtual Office 3.x and earlier versions of Groove convert dates and times between affected time zones and Coordinated Universal Time (Greenwich Mean Time). These versions of Groove use the IBM International Components for Unicode (ICU) library for time zone data. Part of the time zone data is the DST transition rules for time zones. When Groove Virtual Office starts, it queries Windows to determine the local time zone of the computer. Then, Groove Virtual Office matches the time zone to the corresponding ICU time zone data. Groove Virtual Office uses the ICU time zone data in the following operations:
 * Groove Virtual Office converts local time to Coordinated Universal Time (UTC) when Groove Virtual Office saves time stamps.
 * Groove Virtual Office converts UTC to local time when Groove Virtual Office displays time stamps.

Beginning in 2007, the built-in ICU time zone data in Groove Virtual Office 3.x and in earlier versions of Groove is no longer correct for affected time zones because the DST transition rules are obsolete.



MORE INFORMATION
Calculations that Groove Virtual Office performs with ICU data for affected time zones may return incorrect results. Typically, you experience one of the following symptoms:
 * Transmitted time stamps in the extended DST period display on other computers as one hour later than they do on your computer.
 * Received time stamps in the extended DST period display on your computer as one hour earlier than they do on the computer on which they were created.

Groove 2007 uses Windows time zone data. Because Groove 2007 uses the Windows data, it is not affected by the new DST rules if the following conditions are true:
 * Workspace members use Groove 2007 on a Windows Vista-based computer, on a Windows XP-based computer that is updated to accommodate the new DST rules, or on a Windows Server 2003-based computer that is updated to accommodate the new DST rules.
 * Workspaces are created in Groove 2007.

For more information about how to correct problems with Calendar tool entries and with Meetings tool entries in Groove 2007 and about how to compensate for problems with Calendar tool entries and with Meetings tool entries in Groove Virtual Office 3.1, click the following article number to view the article in the Microsoft Knowledge Base:

932607 How to correct time differences in Groove Virtual Office 3.x and Groove 2007 tools that are caused by the extended daylight saving time periods starting in March 2007

Time stamps that are created in Groove Virtual Office display correctly if the following conditions are true:
 * Time stamp recipients are located in the same time zone as the creator of the item.
 * Time stamp recipients use Groove Virtual Office 3.x or an earlier version of Groove.

In this scenario, Groove Virtual Office applies the same calculations on both computers when it converts between local time and UTC. The calculations may be incorrect. However, the calculations are symmetrical. Because the same calculations are performed on both computers, the time stamps display correctly in local time.

In any other scenario, the time stamps may be off by one hour. The following are examples of situations in which you experience this symptom:
 * A Groove Virtual Office user sends a message to a contact in another time zone. The recipient sees an incorrect time stamp in the message.
 * A Groove Virtual Office user views a Discussion item that was created by a Groove 2007 user. The Groove Virtual Office user sees an incorrect time stamp in the Discussion item.

Microsoft does not plan to fix this issue in Groove Virtual Office 3.x or in earlier versions of Groove. To resolve this issue, upgrade to Groove 2007.

Additional query words: Groove2007 GVO

Keywords: kbhowto kbexpertisebeginner kbinfo KB934800

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