The odds are good that the appointments you’ve made with US or Canadian associates through Microsoft’s Exchange or IBM’s Lotus Notes or Domino are going to be off by an hour in the last three weeks of March 2007. Your legacy Java runtime environments also will likely produce incorrect time-sensitive results.

Why? Buried among the hundreds of provisions in the 1,700 pages of the United States’ Energy Policy Act of 2005 is a modest change to the rules that establish when Daylight Saving Time starts and ends. The changes, which the government ostensibly implemented as part of a federal energy conservation effort, require that beginning in 2007, Daylight Saving Time (DST) start three weeks earlier and end one week later than in previous years.

Does the US DST 2007 impact only US computer users? The short answer is no. Organizations and companies with locations, customers, and users in Canada or the US might need to take corrective action. This could include not only large multinational organizations but also international banks, airlines, transportation companies, and government regulators and security agencies. With globalization, many applications and services that companies rely on might not be housed locally, where the users are; they can be located in data centers almost anywhere around the world.