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Chromeleon News: Daylight Saving Time and Chromeleon

2007 Change to U.S. Rules for Daylight Saving Time

In 2005, the U.S. government passed a package of energy-related laws, including one that changes the start and end of Daylight Saving Time (DST) in the U.S. Under the new rules, which take effect in 2007, DST will begin 3 weeks earlier (at 2 a.m. on the second Sunday of March) and end one week later (at 2 a.m. on the first Sunday in November).

Because many computer systems and software must manage dates and times, they can be potentially affected by the change to the DST rules. Computer users (or their Information Technology support staff) should ensure that their computers and software will not be adversely affected by the change.

The change to DST rules will not directly affect the Chromeleon® software, which gets its date and time information from the Windows operating system. However, Chromeleon users in the U.S. do need to ensure that their Windows installation has been updated so that its automatic clock changes conform to the new DST rules.

Microsoft has already published updates for Windows that implement the new DST rules; updates can be downloaded from the Microsoft web site: http://support.microsoft.com/kb/928388

Before installing these updates, people should be aware of potential issues with Microsoft Outlook and plan accordingly. This article provides the relevant details: http://support.microsoft.com/kb/931667

Other Daylight Saving Time Issues

All Chromeleon users should be aware of the following general issues that relate to DST changes in general:

Time stamps in sequences and audit trails from the day a clock change occurs may appear to have gaps (in spring) or overlapping records (in autumn); it is important to note that some of the records represent Standard Time and others represent Daylight Saving Time. Chromeleon records the clock changes in the Audit Trails so that the two types of records can be readily discerned.

Chromeleon events that have been scheduled to occur at specific times close to a clock change may be affected:

Online Transfer Agent events that have been scheduled run in the hour just before the autumn clock change may execute a second time after the automatic clock change occurs, if the events are of the type that could be executed more than once.

If the Datasource Unavailability feature has been used to schedule an offline period that crosses a clock change, care should be taken to ensure that all related computer systems (for example, a Chromeleon workstation and a separate database server) are set up to enact the clock change at the same time, so that backup processes do not get impacted.

Care should be taken when comparing data acquired on Chromeleon systems installed across different states and countries, because DST rules are often different in different regions. For example, Hawaii and most parts of Arizona do not observe Daylight Saving Time, and the DST changeover dates in Europe are different from those in the U.S.

Additional Information

The resources referenced by the links below provide additional information about DST. This listing does not constitute any endorsement or recommendation by Dionex; the links are provided only for your convenience.