Recurrence calculation mode. This field only takes effect when repeatFlag is present.
"0" (REPEAT_FROM_DUEDATE): Repeat from the original due or scheduled date. The next occurrence is based on dueDate and repeatFlag, for fixed schedules such as "every Monday".
"1" (REPEAT_FROM_COMPLETETIME): Repeat from the completion date while preserving the original time of day, for rules such as "3 days after completion". No next occurrence is generated without a completion time.
"2" (REPEAT_FROM_DEFAULT): Default calendar recurrence. It uses the task time zone, skips expired historical occurrences, and advances to the next applicable occurrence. The server usually uses "2" when this field is omitted or empty.
Both "0" and "2" follow calendar or scheduled recurrence rules, but "2" advances from the current date in the task time zone and is the recommended default for ordinary daily, weekly, or monthly recurrence.