What is meaning about "Special Periods" in Planning Calendar?
Is exceptional dates shown in "Special Periods" if I input exceptional dates in weekly?
If you integrate a factory calendar from ECC or S/4, there in transaction SCAL you see the calendar definition. if the ECC calendar has a "special rules" maintained, that shows up in IBP as "Special Periods"
This is useful if you want to have e.g. a calendar that has a working day only every first of the month ("AN" in ECC), then you do have no workdays maintained at all, but all as additional special periods for working days.
You can achieve the same in IBP with the "Exceptional Dates" , which can be mass-pasted (check upper right corner for the EXPORT and the PASTE buttons)