Changes in Daylight Savings Time

Most of you are probably already aware of the legislative change affecting daylight savings in North America. In any event, the nub from an internal note:

The U.S. Energy Policy Act of 2005, passed by the U.S. Congress July, 2005, extended Daylight Saving Time (DST) in the U.S. by approximately four weeks. This change was similarly adopted by the Government of Canada in order to harmonize time zones across North America. As a result, beginning in 2007, DST will start three weeks earlier on March 11, 2007, and end one week later on November 4, 2007, resulting in a new DST period that is four weeks longer than previously observed.

(slight correction by the way – time is governed by the provinces in Canada – see for example the relevant Ontario regulation).

Apart from changing your clocks, you should make a note of whether any patches or updates to your computer systems are required. I know I’ve already seem some traffic on how MS Outlook and Blackberry stuff might need patches as a result of the change. You might also want to highlight this when making appointments during the changed period.

In addition to that, there are also some articles, such as the one in Technology Review, that warn of other potential glitches:

Cameron Haight, a Gartner Inc. analyst who has studied the potential effects of the daylight-saving bug, said it might force transactions occurring within one hour of midnight to be recorded on the wrong day. Computers might serve up erroneous information about multinational teleconference times and physical-world appointments.

”Organizations could face significant losses if they are not prepared,” the Information Technology Association of America cautioned this week.

Dave Thewlis, who directs CalConnect, a consortium that develops technology standards for calendar and scheduling software, said it is hard to know how widespread the problem will be.

That’s because the world is full of computer systems that have particular methods for accounting for time of day. In many, changing the rules around daylight saving is a snap, but in others, it may be more complex.

”There’s no rule that says you have to represent time in a certain way if you write a program,” Thewlis said. ”How complicated it is to implement the change has to do with the original design, where code is located.”

…and don’t forget international stuff:

Also, the change originated in the United States and is being followed in Canada, but not most other nations. That could befuddle conferencing systems and other applications that run in multiple countries at once.

Update: A great and concise article on slaw with more details and better links on the changes in DST.