Some major IT vendors are releasing software patches and fixes designed to handle the earlier start of US daylight-saving time, which takes effect 11 March.

But others have not made clear how the time change will affect users of their applications.

Microsoft’s Windows Vista operating system already includes the updated DST rules, but earlier versions of Windows will need to be changed. For Windows XP Service Pack 2, Windows Server 2003 and Windows Server 2003’s Service Pack 1, the company will release a combined global time-zone update that will include modifications for the DST change in the US.

Earlier versions of Windows, including XP Service Pack1 and NT 4.0, are no longer supported but can be patched manually using Microsoft’s Tzedit.exe utility, which allows administrators to create and edit time-zone entries for the date/time settings in the Windows Control Panel.

Other affected Microsoft products include Windows Mobile, SharePoint Services, Exchange Server, Outlook, BizTalk Server and the Dynamics customer relationship management (CRM) applications, according to the company. Some patches are available now, and the remainder are scheduled to be released by early March.

A detailed summary of the effects of the DST changes on Microsoft products is available on the company’s website.

Sun Microsystems said it is offering free patches for Solaris Versions 8, 9 and 10, but the company will charge a fee for patches for Versions 5, 6 and 7 of the operating system.

Patches will also have to be applied to Java technologies, including the Java Runtime Environment, Sun said. More recent JRE versions already include new time rules designed to handle the DST changes, according to the vendor. Older versions can be replaced with the newer, corrected versions, or systems administrators can download Sun’s TZupdater tool to update Versions 1.4 or later of the JRE.

Users of older Solaris releases also have another option: At least one third-party service and support vendor, Terix Computer Service, has announced free software that updates the DST rules in Solaris Versions 5, 6 and 7.

Details about the effect of the DST changes on a wide range of IBM products can be found at a special DST Web site that the company has set up. The IBM website also provides information about related issues involving Java, specific information about running IBM products with Windows, and a detailed FAQ on the DST issue.

Some IBM products can be updated now, while other applications will include DST updates in their next regularly scheduled maintenance releases, according to the company.

Both Cisco Systems and BEA Systems said they have posted information about their products and the DST change on their websites.

Other vendors, including HP, Oracle and SAP, didn’t provide more specific information about how their products will be affected by the earlier start of DST.

The changes are one of the many provisions of the US Energy Policy Act of 2005 and will mean that US DST will begin almost one month earlier on the second Sunday in March (instead of the first Sunday in April) and end on the first Sunday in November (instead of the last Sunday of October). This means, for example, that between 11 March and 25 March this year there will be a six-hour time difference between London and New York, instead of the normal five hour difference, and a seven hour difference between cities such as Frankfurt, Paris, Madrid or Milan and New York instead of their normal six hour difference.

Analyst firm Gartner has said the impact will extend outside of the US and any organisation that interacts with US business partners will also need to undertake a review of their time-related systems. The impact on such system could affect the synching of calendaring applications, travel schedules, batch processes, security permissions and banking, trading and billing transactional errors.

“Few vendors have centralised repositories of patch and related information although patches for major operating systems and other infrastructure components appear to be readily available,” said Will Cappelli, research vice president at Gartner.

“This is a minor problem compared to the big code changes required in the recent past for issues like Y2K or the Euro conversion. However, significant business damage and liabilities could occur from applications performing their processing at the incorrect time if organisations do nothing,” he said.

Additional reporting by Miya Knights