The calendar defines the default periods for a year. Additional periods can be defined as a roll-up of the periods of the year. Only 5 years of data should be carried at a time. Works with the period ID to uniquely identify a period. If this element is omitted or has a value of 0 then it is the actual period. This element is used to store 'Normal', 'Adjustment', or 'YearEnd' period types.