CalendarCalc for VFP is a set of classes that handle calendrical information and calculations. There is a base class, named CalendarCalc, from which the actual calendar classes derive (that is, the ones for a specific calendar system, such as Hebrew, or Persian, or Gregorian).
Calendar events (natural/astronomical, civilian, religious, of any kind, including personal) can be attached to a calendar object through the instantiation of Calendar Events Processor classes.