Leap year bug sparks new alarm

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Leap year bug sparks new alarm

Monday 21 February 2000

Businesses were yesterday warned to watch out for new Y2K-related computer software problems - hard on the heels of the millennium bug proper.

On 29 February some computer operating systems could go haywire as they fail to recognise that 2000 is a leap year.

The glitch is due to a quirk of the Gregorian calendar. Usually leap years come every four years but, at the turn of each century, February only has 28 days instead of 29. According to this rule, we should not be in a leap year, and February 2000 should have only 28 days.

But every 400 years the rule does not apply, which makes this year a leap year after all and tacks an extra day on to February.

Many computer programs were designed to expect 2000 to follow the 100-year principle and will not recognise 29 February.

After 28 February, these systems may move straight to 1 March, or permit invalid non-existent dates such as 30 or 31 February.

As a result, the day of the week will become incorrect, and some weekdays will become weekends, and vice versa. Systems could malfunction and the knock-on effects could last into 2001.

Action 2000, the independent body set up to advise businesses on the millennium bug, has identified 21 software packages that will not recognise 29 February properly.

Most can be modified to overcome the problem, but some may need to be replaced. The packages include Windows 95, Windows NT Server, Outlook and four versions of FileMaker Pro. Action 2000 warned that any system using dates could be disrupted.


-- Martin Thompson (mthom1927@aol.com), February 21, 2000

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