Daylight time change brings mini Y2K to computers
Last Updated: Wednesday, February 14, 2007 | 9:26 AM ET
The Associated Press
For three weeks this March and April, Microsoft Corp. warns that users of its calendar programs in Canada and the U.S. "should view any appointments ... as suspect until they communicate with all meeting invitees."
Wow, that's sort of jarring — is something treacherous afoot? Actually, it's a potential problem in any software that was programmed before a 2005 law decreed that daylight time would start three weeks earlier and end one week later, beginning this year.
The U.S. Congress decided that more early evening daylight would translate into energy savings. Most Canadian provinces and territories have decided to follow the U.S. plan to avoid headaches that may arise, particularly for trade and travel. But a new set of problems await in the technological world.
Software created earlier than the August 2005 decree is set to automatically advance its timekeeping by one hour on the first Sunday in April, not the second Sunday in March (that's March 11 this year).
The result is a glitch reminiscent of the Y2K bug, when cataclysmic crashes were feared if computers interpreted the year 2000 as 1900 and couldn't reconcile time appearing to move backward. This bug is much less threatening, but it could cause head-scratching episodes when some computers are an hour off.
The problem won't show up only in computers, of course. It will affect plenty of non-networked devices such as some digital watches and clocks that store the time and automatically adjust for daylight time. But in those instances the result will be a nuisance (adjust the time manually or wait three weeks) rather than something that might throw a wrench in the works.
Cameron Haight, a Gartner Inc. analyst who has studied the potential effects of the daylight time 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 time 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."
Further confounding matters, there are lots of old computer programs whose original vendors don't support them anymore, meaning there's no repair available. Some gadgets, such as VCR clocks, may not have any mechanism to update their software.
Also, the change originated in the United States and is being followed in Canada, but not most other countries. That could befuddle conferencing systems and other applications that run in multiple countries at once.
A common fix is a "patch" that reprograms systems with the updated start and end dates for daylight time. Some of these updates are targeted at specific systems, while others have wider implications — such as one from Sun Microsystems Inc. for older versions of the Java Runtime Environment, which often fuels applications on computers and web pages.
Microsoft planned to send its daylight patch to Windows PCs with the "automatic update" feature on Tuesday. Users with automatic updates turned off should download the patch from Microsoft. New machines running Windows Vista are immune to the problem, however, since Vista was finalized after the 2005 law passed.
For those with older systems who store their dates on Outlook or other desktop-based calendar programs, Microsoft advises going online and downloading a small program known as "tzmove" — Time Zone Move — that can retrofit all previously booked appointments to the new daylight time rules. Other vendors offer similar tools for their systems.
