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 DST Changes in Canada and the United States for 2007
Overview
FirstClass has a number of different functions which depend on accurate time calculation, including calendar events, message history, etc. Upcoming changes to the calculation of Daylight Savings Time may affect certain FirstClass sites running older versions of the FirstClass Server or Client.
Details
FirstClass stores all dates in a consistent manner on the FirstClass server, and the dates are converted to the user's local time by the client when they are displayed. In a perfect world, this would simply be calculated by taking the user's time offset from the server and adding or subtracting as appropriate. However, this simple model is complicated by the fact that some locales adopt Daylight Savings Time, thereby changing their offset at certain times of the year. This year, things are further complicated by the fact the the adoption date of Daylight Savings Time has been changed.
Note that all of this discussion is independent of how your computers are actually converted to DST. If you are running the latest OS versions (NB: there is an update for Windows and OSX - keep in mind that only up to OSX 10.4.6 is fully supported by us and that the DST update WILL work on that version), this conversion ("springing ahead" and "falling back") should be done automatically. If you are not running the latest OS version, you may have to manually enable DST mode. FirstClass will work fine no matter how the OS is changed to DST mode.
So, there are a number of very distinct cases you need to worry about, and they involve the relative time zones of your server and your clients. In particular, they involve whether your server is in a time zone which observers Daylight Savings Time, and whether your users are in a time zone which observes DST.
If your server and users are not in North America...
...then you should be able to continue to use any version of FirstClass with no problems.
If your server and users are all in the same time zone, and that zone observes DST...
...then you should be able to continue to use any version of FirstClass with no problems.
If your server and users are all in the same time zone, and that zone does not observe DST...
...then you should be able to continue to use any version of FirstClass with no problems.
If your server and users are in different time zones, and all of those time zones observe DST...
...then you should be able to continue to use any version of FirstClass with no problems.
If your server and users are in different time zones, and the server time zone observes DST but the client time zone does not...
...then there may be a problem. Specifically, for the period of time between the new DST conversion date (March 11) and the old DST conversion date (April 1st), users of older versions of the FirstClass Client will see the times on their calendars off by one hour. If the server is also an older version, calendar reminders will also be off by one hour.
If your server and users are in different time zones, and the server time zone does not observe DST but the client time zone does...
...then there may be a problem. Specifically, for the period of time between the new DST conversion date (March 11) and the old DST conversion date (April 1st), users of older versions of the FirstClass Client will see the times on their calendars off by one hour. If the server is also an older version, calendar reminders will also be off by one hour.
As always, we recommend that you run the latest version of FirstClass to ensure maximum reliability and security.
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