Beginning in 2007, daylight saving time (DST) has been extended in the United States. DST started on March 11, 2007, which was three weeks earlier than usual, and will end on November 4, 2007, which is one week later than usual  This results in a new DST period that is four weeks longer than in previous years.


Y2K + 7?
The Energy Policy Act of 2005 changed the time change dates for Daylight Saving Time. Beginning in 2007, DST will begin on the second Sunday of March and end the first Sunday of November.

The concern among many is that software including Windows and applications that rely on time will be left set at the wrong time.   All the attendant wrong time issues that were first discussed with regards to the change in millennia could surface again when the time changes in March.


Windows O/S

As far as updating Windows with the new DST rules, Microsoft® has hot fixes available for the more recent operating systems (XP, 2003 and Vista).

To obtain these fixes see the Microsoft Knowledge Base (KB) article 928388, 2007 time zone update for Microsoft Windows operating systems

Earlier versions of Windows can be manually updated using the tzedit.exe utility or other techniques documented in Microsoft Knowledge Base article 914387

February 2007 cumulative time zone update for Microsoft Windows operating systems in KB 931836
Before you apply the 2007 cumulative time zone update for Windows operating systems, be aware of potential issues that may affect Microsoft Office Outlook.

For a general discussion about preparing computers for US changes in DST in 2007 or here


 Addressing daylight saving time using the Outlook Time Zone Data Update Tool in KB 931667


Issues with calendaring in Microsoft Exchange are discussed in the Lotus notes section below.

Beagle Software


ClockWatch is Beagle Software's Clock Synchronization product for Windows. Since it synchronizes clocks from standard time to local time, it must know if the local clock is currently using DST.

ClockWatch uses the DST and time zone value set in Windows. Whatever time zone and DST setting that is set in the Windows Control panel is used in ClockWatch for time and DST.

So as long as Windows is aware of the DST change, our ClockWatch products will be OK. To check whether your Windows version is correct, see the discussion above.

DocuClock time stamping system uses ClockWatch for time synchronization so the product is not affected.


Both Lotus Notes and Lotus Domino® are affected by the change in DST

How Calendar Entries are Affected:

Systems updated to the new Daylight Saving Time rules
Any calendar entry that falls within the extended Daylight Saving Time (DST) period created before the application of the extended DST rules will appear incorrectly after the extended DST rules are applied. Entries that fall between March 11, 2007 and March 31, 2007 and those that fall between October 28, 2007 and November 3, 2007 will appear an hour later than originally scheduled.

Note: The DST change will not affect only Lotus Notes and Domino®. It is a calendaring issue which will affect many operating systems and applications, including Microsoft® Exchange and any other time-zone-aware calendar systems.

For example, if a user in the United States creates a calendar entry (prior to the application of the extended DST rules) for 10 AM on Monday, March 12, 2007, the entry will display as described below once the modified DST rules are applied.

The StartTime field and EndTime fields are used to portray the start and end time settings in an open document but not in the view(s). The StartTime and EndTime fields are designed to retain only a time portion, and as such they are not affected by the changes to the DST rules. This is working as designed.

Note: There is an exception with meeting entries which have been saved as Draft. In this case, the StartTime field and or the EndTime field may display at the expected time or an hour later depending on how the times were originally selected. If either of the time settings were set using the Time Picker or are manually entered, then the values for the StartTime and/or EndTime fields will consist of only a time portion and the value for the field(s) will be static and unaffected by changes to DST rules. If a setting was left at the default time when the document was created it will consist of date, time, and time zone; the entry will be dynamic and will be affected by the change to DST rules. In Draft entries, even if the StartTime or EndTime field values are static it does not mean that other fields derived from them will be static. This means it may be possible that an open C&S document will reflect the expected time, but the same document observed from the view will reflect times that are off by an hour. The fact that the StartTime and EndTime fields record only a time portion under the described scenario is working as designed.


The effect of DST change on Java is significant. Time zone information is obtained from a set of files stored internally by the Java Virtual Machine (JVM) and applied to dates as required. Since this information is statically stored in the Java Runtime Environment, older versions of Java do not know about the changes and will display the wrong time for the USA throughout most of March 2007. Forward date information will already be wrong if it refers to dates in that period.

Java 5 update 5 and earlier
Java 1.4.2_10 and earlier
Java 1.3.x

Java 5 update 6 or later
Java 1.4.2_11 or later

Updated 10/15/2007

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Copyright © 2007 Beagle Software. All rights reserved
Last reviewed March 09, 2007