The calendar schema is used to associate people and objects to a period of time. The calendar type is based on the iCalendar specification. Currently, only the event type is defined, but the ToDo and the Journal type can be added in the future as business requirements dictate. The model was extended to allow objects other than people to be associated with an event. This attribute is used to define the purpose of the calendar. EventRole should be 'Organizer', 'Mandatory' or 'Optional'. This may become an enumeration at a later period. These are the people that are associated with the event. Values should be limited to FREE, BUSY, BUSY-UNAVAILABLE, and BUSY-TENTATIVE This identifies the notification method. This element is used to identify an organizer when the organizer is not a participantin the event.