Thursday, February 22, 2007

Impacts to applications due to changes to the start and end dates for Daylight Saving Time (DST)

I received this email from the Microsoft US Development Center. It warns about changes to the start and end dates for Daylight Saving Time (DST) as of Spring 2007. It talks about impacts to existing applications and how applications using .NET Framework will be affected. Read on for details.

Dear Valued Microsoft Customer,

In 2005, the United States government passed the Energy Policy Act of 2005. This act changes the start and end dates for Daylight Saving Time (DST) as of spring 2007. These changes may impact the way applications run. Microsoft is releasing an update for Windows through Microsoft Update that reflects these changes.

Developers who use the .NET Framework may find their applications affected if the application uses the time zone information for historical purposes or if they have derived custom classes from System.TimeZone to provide custom time zone information. The standard System.TimeZone class provides a managed wrapper for the underlying Windows Operating System time zone functions.

In addition, developers who use Visual C++ may find their applications affected if they use the CRT time functions, or the TZ environment variable. Microsoft is currently working on a fix for this issue and will post information about its availability on the Visual Studio Support page.

Most applications that use these affected classes will not need to be modified as this update will ensure that the correct data is provided seamlessly to the application. However, applications that use these classes or the underlying Windows API to perform historical time look-ups will need to be modified.

In most cases, developers who have extended the .NET Framework’s time zone support by creating custom time zone classes derived from System.TimeZone, or by direct access to the Win32 API, will not have to update their applications as long as the available updates to the operating system are applied. However, solutions that rely on private time zone data, or that retrieve system time zone information by accessing the registry directly, may need to be updated. Applications that deal with historical time zone data may also need to be updated.

Microsoft advises all developers who make use of time zone data to test their applications against this update to ensure that their applications function correctly.For more detailed information and the latest updates please visit, Preparing for daylight saving time changes in 2007, and KB928388: 2007 time zone update for Microsoft Windows operating systems.

Further Assistance
Microsoft values your business. For more information visit, or contact Microsoft for assistance. A list of phone numbers is located at Microsoft Premier Customers may engage their Technical Account Manager directly.

Please DO NOT REPLY to this email as this is not a monitored inbox. If you have questions/inquiries please visit

This e-mail is intended for distribution within the United States. Please contact your local Microsoft subsidiary for similar offerings outside the US.

Thank you,
Microsoft US Developer Team

Update: An email from MS for updating the mobile devices

Here comes the sun!
Update your Windows Mobile powered device now

You can't deny it-spring is on the way! And this year, along with the sunshine and warmer weather, comes Daylight Saving Time.

Due to Congress's Energy Policy Act, you'll need to remind your Windows Mobile® powered device that clocks will be set forward sooner than usual this year. Make sure your device doesn't fall behind by updating its software now.

To ensure your device is on time, visit and download the necessary updates.

This newsletter was sent by the Microsoft Corporation
1 Microsoft Way
Redmond, Washington, USA

No comments:

Post a Comment