DateTime problem due to DST rule change
The rules covering the start and end of Daylight Savings Time in the US and Canada will change starting in 2007; DST begins earlier and ends later. The TimeZone class rules will be incorrect and calculate local time incorrectly. The current TimeZone class does does not handle cases where the rules vary in different years; updating the rules will create problems with DateTimes in previous years.
Instances of DateTime store the time as GMT (UTC), which is calculated based on the related TimeZone. If DateTimes are created during the periods where the new rules and old rules give a different local time, they will be created with an incorrect internal GMT time. Applications that create future dates are likely to have incorrect GMT times in DateTime instances.
Workaround
GemStone is providing a new TimeZone subsystem, which relies on the public domain zoneinfo database. Applications must be updated to create the new TimeZone class instance/s, and instances of DateTime must be updated to refer to the new TimeZones. In addition, DateTime internal values may require updating. GemStone is providing a customizable script to handle the most common application update requirements.
The new TimeZone subsystem will be provided in all future releases.
Last updated: 12/27/06