iSync: About Syncing Recurrent Events Between iCal and Palm OS Based Devices

To display recurring iCal events on the Palm, the events saved to the Palm device may be modified so they can be represented on the device. Although some fields on the device will be different than those in iCal, the events aren't changed in iCal unless you explicitly change them on the Palm and synchronizes them to iCal using iSync.

For example, if the beginning date of an event needs to be adjusted to display on the Palm device, and the event title is later modified on the Palm, the next time you sync the Palm device, the modified title appears in iCal, but the beginning date will not be changed in iCal. (It will preserve the beginning date of the original event from iCal even though it is shown differently on the Palm.) Conversely, though, if any of the modified fields synced to the Palm are later modified explicitly on the Palm, the changes are synced back to iCal. In the preceding example, if you modified the beginning date of the event, this modification is synced back to iCal.

The cases where an event is modified or represented differently on the Palm are as follows:

• Events in iCal that span multiple days are represented as an all day event on the Palm. These all day events only span one day, the beginning date.

• If an event in iCal repeats yearly on a specific day (such as "1st Sunday in April"), the event will be converted to an event repeating every 12 months on the Palm.
  
  For events in iCal that repeat every n years (where n is 1, 2, 3, and so forth) the event will repeat every (n * 12) months on the Palm. For example, if the event repeats every 2 years in iCal, the event will repeat every 24 months (2*12) on the Palm.
  
  If the event interval is adjusted on the Palm to an even multiple of 12 (such as 12, 24, 36, and so forth) the event will continue to repeat yearly in iCal (1 year for 12 months, 2 years for 24 months, and so forth.) If the interval is changed to a number that is not evenly divisible by 12 (such as every 3 months), the event will be converted to a monthly repeat in iCal.
• If an event in iCal has a recurrence specified yearly on a specific month, and the specified repeat month in iCal is different than the month of the beginning date of the event, the repeat month will be ignored on the Palm and the event will repeat in the same month as the beginning date. For example, if an iCal event starting April 1, 2003 repeats yearly in May on the first Tuesday, the first repeat in iCal will be May 4, 2004 but on the Palm it will repeat on April 1st every year.

• If an event in iCal has a beginning day that is different than the day of the week specified for a monthly or yearly repeat (such as "the first Sunday of every month" or "the second Monday of every January") and the beginning date of the event is on a different day, the beginning date will be converted to match the repeating day when the event is put on the Palm. The event is not modified in iCal unless the beginning date is changed by the user on the Palm.

• For an iCal event that repeats monthly with more than one repeat date (such as "every month on the 1st and 15th of the month"), or repeats yearly with more than one repeat month (such as "yearly on Jan 1st and July 1st") the event will not repeat on the Palm.

• Certain events repeating every few weeks on multiple days of the week may be represented with an alternate Saturday or Sunday on the Palm. The Palm treats Sunday as the first day of the week, but iCal treats Monday as the first day of the week. If an event in iCal starts on a Saturday and is set to repeat on Sat and Sun every two weeks, in iCal it will repeat on the Saturday and the Sunday immediately following. On the Palm, however, the event will repeat on the Sunday one week after the Saturday. This is due to the Palm and iCal representing the beginning of the week differently. The event start date is the same and the repeat directive ("repeat every two weeks on Sat and Sun") is the same, but the Palm behaves differently than iCal with the same data.