The date to start recurrence from (eg. every 3 days from this date), expressed in number of seconds from the first instant of 1 January 1970, GMT. Usually the same as the ”duedate”. If unspecified, the recurrence will be repeat-from-completion, eg. a yearly repeat-on-completion reminder will repeat again on June 1st, 2012 if the user completes it on June 1st, 2011, but will repeat on June 3rd, 2012 if the user only completes it on June 3rd, 2011.