Pinehurst Computer Support, LLC Providing Affordable Computer Support, Hosting Services, Domain Registration, Offsite Backups, and Much More.

Don't Let Your Computer Fall Behind...

In August of 2005, the United States Congress passed the Energy Policy Act, which makes daylight saving time (DST) start three weeks earlier and end one week later.

The law goes into effect this year, which means we will all “spring forward” our clocks at 2:00 A.M. on the second Sunday in March (March 11, 2007).

If you use a recent version of the Windows operating system, you know that normally you don't have to manually change the time for DST. The operating system does it for you.

Even though these versions of Windows are smart enough to know about DST, they're not smart enough to know about the Energy Policy Act, so you'll have to install an update that will make the change.

The only exception for this is Windows Vista. If you buy a new computer that runs Windows Vista, the updates are already installed.

Download and install the update for Windows XP (SP2), Windows Server 2003, or Windows Server SP1

To help ensure that your computer updates correctly on March 11, download the update below that corresponds to the operating system that you use.

These updates will change the time zone data to account for the United States DST change and will take care of other related DST changes, time zone behavior, and settings.

The following files are available for download from the Microsoft Download Center:

Download the Update for Windows XP package now.

Download the Update for Windows XP x64 Edition package now.

Download the Update for Windows Server 2003 package now.

Download the Update for Windows Server 2003 for Itanium-based Systems package now.

Download the Update for Windows Server 2003 x64 Edition package now.

What to do if you use Windows 2000

There is no update for Windows 2000, but you can make the change manually.

All versions of Windows can be manually updated with the tzedit.exe utility which you can use to create and edit time zone entries for the Date and Time settings in Control Panel, especially for daylight saving time.

For more information, see How to configure daylight saving time for the United States in 2007.

What to do if you use Windows XP SP1

Windows XP SP1 is no longer supported. For increased security, go to Microsoft Update to upgrade to Windows XP SP2.

Want more information on this change?

To read more about how this update works, see Preparing for daylight saving time changes in 2007.

Turn on Automatic Updates

Right now, these updates are not a high priority, so they will not be installed automatically. To get updates like these automatically, turn on Automatic Updates.

Published Thursday, January 25, 2007 8:56 PM by Marcelle Amelia

Introduction

In August 2005, the United States Congress passed the Energy Policy Act, which changes the start and end of DST as observed in the United States. Some additional countries/regions are following the U.S. change. As a result, DST will start three weeks earlier on March 11, 2007, and end one week later on November 4, 2007 — resulting in a new DST period that is four weeks longer than previously observed. These dates are referred to in this article as the extended DST period.

Daylight saving time rules

1987 to 2006 Daylight saving time begins (shifts time one hour forward) at 2 A.M. on the first Sunday in April and ends (shifts time one hour back) at 2 A.M. on the last Sunday in October.

Starting in 2007 Daylight saving time begins at 2 A.M. on the second Sunday in March (three weeks earlier) and ends at 2 A.M. on the first Sunday in November (one week later).

In 2007, daylight saving time will be observed March 11, 2007, through November 4, 2007, in areas of the United States and Canada that observe daylight saving time.

In 2007, the additional time period includes March 11, 2007, to April 1, 2007, and October 28, 2007, to November 4, 2007. These dates are referred to in this article as the extended DST period.

Get more information

IT and Exchange administrators can read a more detailed version of this article with additional technical information at Microsoft Knowledge Base article 931667: Addressing daylight saving time using the Time Zone Data Update Tool for Microsoft Office Outlook.

For more information about how to prepare for changes in daylight saving time in 2007 for all affected Microsoft products, see http://www.microsoft.com/DST2007.

Top of Page

Time Zone Data Update Tool for Microsoft Office Outlook

Microsoft has released a program that can update calendar items in Microsoft Office Outlook to accommodate the changes in DST during the extended DST period. This program is called the Time Zone Data Update Tool for Microsoft Office Outlook.

The Time Zone Data Update Tool is available for download at the Microsoft Download Center.

Microsoft Office Outlook 2007, the newest version of Outlook, can automatically update a person's calendar to conform to the new daylight saving time rules. However, the Time Zone Data Update Tool contains additional improvements that are not available in Office Outlook 2007.

For earlier versions of Microsoft Outlook — Outlook 2000, Outlook 2002, and Office Outlook 2003 — the Time Zone Data Update Tool is necessary to update calendar items that occur during the extended DST period defined above.

The following table describes the situations where users should download and run the Time Zone Data Update Tool:

Outlook 2007	Outlook 2000, Outlook 2002, and Office Outlook 2003
Users are not required to download and run the Time Zone Data Update Tool in most instances, but it is recommended because it includes the most recent improvements.	All users should download and run the Time Zone Data Update Tool. Alternatively, in environments running Microsoft Exchange, a special version of this tool may be used by IT administrators to update multiple Exchange mailboxes at one time.

Top of Page

Steps you need to take

Because many calendaring environments have an interconnected system of applications, each of them must be adjusted to accommodate the new DST rules. The sequence to update your computer should be:

Step	Action	Performed by
1	Apply updates to Microsoft Windows operating systems on servers running Exchange servers.	IT administrator.
2	Apply updates to computers running Windows; apply updates to mobile devices used to create or view calendar items.	IT administrator or end user.
3	Apply the Collaboration Data Objects (CDO) update to servers running Microsoft Exchange.	IT administrator.
4	Download and run the Time Zone Data Update Tool to update Outlook calendars that are saved on servers running Exchange and on individual computers.	End users use the Time Zone Data Update Tool. IT administrators use the Exchange version of the update tool.

Note IT and Exchange administrators can read a more detailed version of this article with additional technical information at Microsoft Knowledge Base article 931667: Addressing daylight saving time using the Time Zone Data Update Tool for Microsoft Office Outlook.

Top of Page

How to minimize the impact of the DST change

Ultimately, individual calendar owners are the only ones who can validate that calendars are correct or not. To minimize confusion during the DST shift, follow these simple steps:

1. When organizing a meeting during the extended DST period, type the correct meeting time in the subject line or body of the message (for example, Project planning meeting at 8:30 A.M.).

2. Consider any appointments and meetings in the extended DST period to be suspect. When in doubt, verify the correct time with the organizer.

Top of Page

Why an update is necessary

The Time Zone Data Update Tool is necessary to ensure that the meetings and appointments for which you are the organizer during the extended DST period are shown at the correct times on your and your invitees' Outlook calendars.

Microsoft Office Outlook creates appointments and meetings using Coordinated Universal Time (UTC) format, an international standard 24-hour timekeeping system. For example, an 8 A.M. appointment on March 1, 2007, in Redmond, Washington is saved as UTC 4 P.M. because DST has not yet started on March 1 and Redmond time is 8 hours behind UTC.

When a DST update is made to the Windows operating system to accommodate the new DST definitions, the computer's local time will reflect the change to DST. However, appointments made in the extended DST period will be one hour off because time changes made in Windows do not change UTC time, but rather the local time of the computer. For more information on supporting the DST changes in Windows operating systems, see KB 931836: February 2007 cumulative time zone update for Microsoft Windows operating systems.

For example, when you view an appointment scheduled for 8 A.M. on March 15 in Redmond after updating Windows but before running the Time Zone Data Update Tool, you will see a start time of 9 A.M. because it was originally stored as 4 P.M. UTC, but the local system now recognizes 4 P.M. UTC as 9 A.M. Redmond time (4 P.M. – 8 hours + 1 for DST).

Top of Page

What happens if you do not update Windows or Outlook

If you choose not to install the Windows updates and run the Time Zone Data Update Tool, then during the extended DST period, the impact on your Outlook calendar will be that appointments and reminders will appear one hour off. All-day events will shift and span two days because these events are associated with 24 specific hours rather than an individual date.

Impact between March 11, 2007, and April 1, 2007	Impact between October 28, 2007, and November 4, 2007
Calendar items display one hour later than originally scheduled	Calendar items display one hour earlier than originally scheduled

Top of Page

Tools for updating DST in calendaring applications

Outlook users

The Time Zone Data Update Tool enables you to update the meetings you have organized to accommodate the change in DST rules. In addition to updating the meetings on the organizer's calendar, the tool automatically sends updates to all other attendees. This is necessary so everyone has the correct meeting start and end time.

You must download the Time Zone Data Update Tool from the Microsoft Download Center and then run the tool.

Exchange administrators

The Microsoft Exchange Calendar Update Tool is available for updating selected mailboxes without any individual user interaction. Download the update tool at the Microsoft Download Center.

There are additional items that need to be addressed on computers running in Microsoft Exchange environments by IT administrators. In particular, Microsoft Exchange utilizes Collaboration Data Objects (CDO), which has its own internal table of time zone definitions independent of the local computer definition of a time zone. The CDO update changes the CDO binaries such that they contain the correct time zone information. More information about tools and resources to update Microsoft Exchange for DST can be found here.

Top of Page

Different scenarios in Outlook

Appointments and meetings can be created under the previous DST rules (DST 2006) or after DST rules have been updated in Windows (DST 2007). Likewise, these same appointments can be viewed on computers that continue to operate under DST 2006 rules, or have been updated to reflect DST 2007.

When you view items on computers that have DST rules that are different than the one on which the item was created (for example, an appointment created with 2006 DST rules and viewed with 2007 DST rules), then the item will be shifted by an hour.

There are four different scenarios:

Scenario 1: Appointments and meetings created under DST 2006 rules and viewed with DST 2006 rules

Summary	The Windows time zone update is not installed and the Time Zone Data Update Tool has not been used. This is a common case for anyone who does not use Microsoft Update and has not taken any action to address DST changes.
Description	Appointments and meetings are created that fall in the extended DST period on computers prior to updating them to reflect the new DST rules. And, these calendar items are viewed in Outlook on computers that do not have the Windows DST update applied.
Results	Calendar items display at the correct time, but the system time on the computer will be off by one hour during the extended DST period.
What to do	Update Windows with the new daylight saving time rules. This update will be available on Microsoft Update. Following the update, Scenario 2 will be common.

Scenario 2: Appointments and meetings created under DST 2006 rules and viewed using new DST 2007 rules

Summary	Updated time zone rules have been applied to Windows, but the Time Zone Data Update Tool has not been run to address appointments previously created. This scenario can also occur if new calendar items are created on mobile devices or other computers that haven't been updated for DST, but the items are subsequently viewed on a computer that has been updated.
Description	Appointments and meetings that fall within the extended DST period were previously created on devices under DST 2006 rules but they are then viewed on devices that have been updated to reflect DST 2007 rules.
Results	Appointments and meetings where you are the organizer are an hour off during the extended DST period. Meetings where you are an attendee might or might not show up at the correct local time.
What to do	Run the Time Zone Data Update Tool to update appointments and meetings where you are the organizer to reflect the new DST rules. Meeting updates are automatically sent to the other attendees. Refrain from creating new meetings during the extended DST period from computers and mobile devices until they have been updated for the new DST rules. For meetings during the extended DST period in which you are an attendee and which have not been updated by the meeting organizer, directly contact the organizer to confirm the correct time.

Scenario 3: Appointments and meetings created or updated using new DST 2007 rules and viewed on a non-updated device still using DST 2006 rules

Summary	Other users have updated their computers to reflect new DST rules, and have sent you meeting invitations that occur during the extended DST period. However, you have not updated Windows on your computer for the new DST rules. Alternatively, you have updated your computer to reflect the new DST rules, and have run the Time Zone Data Update Tool, but are now viewing the calendar on another computer or mobile device that has not been updated.
Description	Appointments and meetings were created on a computer that was updated to use new DST 2007 rules, but someone is viewing the calendar items on a computer that continues to run under DST 2006 rules.
Results	Appointments and meetings for which you are the organizer are an hour off during the extended DST period. Meetings where you are an attendee might or might not show up at the correct local time, depending on whether the organizer has run the tool or not.
What to do	Update computers and mobile devices with the Windows DST update.

Scenario 4: Appointments and meetings created or updated to reflect new DST 2007 rules and viewed on computers updated to use new DST 2007 rules

Summary	Windows is updated for the new DST 2007 rules and the Time Zone Data Update Tool has been run to address previously created appointments. The computer and mobile devices which are used to view and create appointments are updated with the new DST 2007 rules. Appointments and meetings where the user is an attendee have been updated by meeting organizers who have updated their systems to reflect new DST rules.
Description	Appointments and meetings were created using DST 2006 rules and were later updated using the Time Zone Data Update Tool, or were created after Windows was updated to reflect the new DST rules and then viewed on computers that are updated for DST 2007 rules.
Results	Appointments display correct times during all time periods.
What to do	No action required.

As the above scenarios illustrate, there are cases where appointments and meetings might still reflect incorrect times even after Windows is updated for the new time zone rules and the Outlook Time Zone Update tool is run. In particular, make sure you watch for the following scenarios:

Appointments where the user is an attendee which was sent by an organizer who has not yet updated their operating system and run the Time Zone Data Update Tool. User is viewing their appointments on other computers and mobile devices that have not been updated with new DST rules.

Note Calendar items in Delegate Access situations or in any additional Exchange mailbox in your Outlook profile are not updated by the Time Zone Data Update Tool. Only your own calendar items are modified.

Top of Page

Frequently asked questions (FAQs)

How is the target time zone reflected in Outlook items?

Single instance appointments and meetings are stored in UTC. The UTC time at which they are stored is determined by the computer that is creating them. In versions of Microsoft Outlook previous to Outlook 2007, there is no indication of what time zone such an appointment or meeting was created in. Outlook 2007 does store target time zone information on single instance items. Recurring appointments and meetings have the full time zone definition embedded in their data. In other words, the appointment or meeting itself understands exactly what the time zone definition and DST transition dates for it should be.

How does the Time Zone Data Update Tool work?

If the tool detects that there are new rules for a time zone, it can automatically attempt to transition any appointments and meetings that are affected by the change into the new version of the time zone. There are two cases:

Recurring calendar items These items have the exact time zone definition embedded in them so the tool can do a comparison of time time zone definitions and, if it matches, rewrite the appointment or meeting with the new version of the time zone information.

Single-instance calendar items These items are more complicated because, previous to Outlook 2007, they contained no time zone information. This makes it is impossible for the tool to determine whether or not the item needs updating. The tool currently assumes that any single-instance calendar item in the extended DST period were generated using the previous time zone rules and offers to update them. Since single-instance calendar items do not contain any time zone information, those items that were targeted at an unaffected time zone but happen to fall within the affected dates of the time zone being transitioned will also be identified by the tool as requiring an update. In these cases, only the appointment or meeting owner can absolutely determine whether a particular appointment should be updated.

When will my Windows time zone definitions be updated if I'm using Windows Vista?

Windows Vista already includes the new DST rules and automatically updated time zone definitions on January 1, 2007. Other Microsoft Windows operating systems will receive a DST update via Microsoft Update. For more information, see Micrososft Knowledge Base article KB 931836.

When should I run the tool?

The tool can be run manually at your discretion after the Windows time zone definitions have been updated. It is preferable to run the Outlook/Exchange tool as close as possible to the time at which the Windows time zone patch is applied (to all computers) since that will minimize the likelihood of having single-instance calendar items that were created after the Windows time zone update was applied, but before the Outlook/Exchange tool was run.

Should I run the tool if I have Outlook 2007?

Outlook 2007 has this functionality already embedded in it. You are not required to manually run the tool since Outlook 2007 automatically detects a time zone definition change and automatically prompts you to complete the update process. However, the tool contains updated enhancements that might improve your experience and is the preferred method of updating your calendar. We recommend that you cancel the dialog boxes that appear automatically in Outlook 2007 and follow the instructions to download and run the tool instead.

Which calendar items does the Time Zone Data Update Tool attempt to update?

Due to the manner in which target time zone is reflected in appointments and meetings the tool attempts to update all single-instance items that fall into the affected date ranges and all recurring appointments that have instances in the affected date ranges and were not created for other time zones. It attempts to update all such single-instance calendar items because, unless they were created in Outlook 2007 or have already been updated by a previous run of the tool, the tool cannot identify the time zone to which they are targeted.

Why doesn't the Time Zone Data Update Tool update all of my affected meetings?

The tool only updates meetings for which you are the organizer and then automatically sends updates for those meetings to all other attendees. This is required so that all meeting attendees have the correct start and end time of the meeting.

What are some situations in which I might want to run the tool multiple times?

It is a good idea to run the tool multiple times if you continue to create appointments and meetings from computers or devices that do not contain the latest daylight saving time rules. A similar situation occurs if, after running the tool, a recurring appointment or meeting that did not have any occurrences in the extended DST period is modified so that an instance now occurs within the extended DST period. The tool originally would not update the recurrences because no instances were affected by the DST changes. Now that such occurrences exist, the tool needs to be run again so that it can find and update the time zone information appropriately.

What are some situations in which I want to avoid running the tool multiple times?

If you use an Exchange account, make sure that you run the tool only from one computer at a time. Attempting to update the same calendar from multiple computers simultaneously might lead to conflicts and other problems. Due to synchronization issues, do not run the tool with your Exchange account if you are working offline. Only run the tool when connected to the server.

How does the Exchange tool compare to the Time Zone Data Update Tool?

The Exchange tool allows an Exchange administrator to apply the time zone update in silent mode to a set of selected mailboxes on the server running Exchange. Each person with an Exchange account will not have the opportunity to clear selections for appointments that do not need updating. The Exchange tool only affects calendars that are saved on the server running Exchange. Any calendars that are saved in a Personal Folders file (.pst) can only be updated by the Time Zone Data Update Tool.

What will happen to resource calendars?

Updates are sent for meetings based on the time at which the tool is run. If a room or resource is booked in two contiguous time slots and it receives the update for the later meeting that moves it back an hour first, the update will be rejected because the change would create a conflict with the first meeting. Accordingly, you should be aware of potential conflicts on shared calendars when multiple people are updating their DST rules.

What happens if I use multiple computers, not all of which are updated?

Particular attention should be made when using a combination of updated and non-updated computers. Appointments and meetings created with non-updated time zone information and viewed on an updated computer will be erroneous during three weeks in the spring (March 11, 2007, to April 1, 2007) and one week in the fall (October 28, 2007, to November 4, 2007) and you will have to re-run the tool in order to update them. And, if you have since created other single-instance appointments and meetings on the updated computer, the tool is likely to try to erroneously update them as well.

What happens if I run the tool on one of the SharePoint calendars that I'm connected to?

Connected SharePoint calendars are read-only in Outlook 2003. The Outlook/Exchange tool will incorrectly modify these calendar items on your calendar, but the updates will not be pushed to the SharePoint server. The two calendars will be out of synchronization. Because running the tool on a connected SharePoint calendar in Outlook 2003 is a custom action, this situation will not happen as a default case.

Top of Page