Making appointments repeat

Appointments and to-do items can be set to automatically repeat every day, week, month, or year.  They are set to repeat through the Inspector panel's Repeat display:

To make an appointment repeat:  1 Select the appointment in its schedule or to-do list.  2  Select Repeat from the Inspector panel's pop-up list.  3 Choose the repeat interval.  4 Optionally, select the repeat frequency by dragging the slider.  5  Set the start and end dates of the repeat period by typing the new date into the fields or by using the arrow buttons to increment or decrement the date components.  6 Press the Set button to make the changes take effect, or press the Revert button to discard the changes.

The day of the week on which weekly appointments occur is determined by the day of the week of the start date.
Monthly appointments occur on the day of the month of the start date.  If that day is greater than 28, the appointment will not occur in all months.  It will not occur in months that have fewer days than the appointment day.
The repeat frequency determines how often the appointment occurs, according to its repeat interval.  For example, if the interval is set to daily and the frequency is set to 3, the appointment will occur every three days.  Bi-weekly or bi-monthly appointments can be created by setting the frequency to 2 and the interval to weekly or monthly.
Changing an appointment's start date will make it disappear from the schedule it was in if the new start date causes the appointment to not occur on the date it used to occur on.
If a repeating appointment is moved to a different time on a schedule, all of its occurrences will have the new time.
If a repeating appointment is moved to a different date, all of its occurrences will be affected by the new date.  For example, moving a weekly appointment from a Monday to a Tuesday will cause all of its occurrences to move to Tuesdays.  Likewise, moving a monthly appointment from the10th to the12th will cause all of its occurrences to move from the10th to the12th.
If a repeating appointment is moved to a date before its start date, its start date will be changed to the new date.  Otherwise, the start date will only be adjusted to reflect the new day of the week or day of the month.
Repeat intervals of the first or last week of a month, or other less regular intervals, are not currently supported.