Here you select the delivery period that this part will have when you place the order for this forecast row during requirements planning. By default, the system will enter the period that equals the previous forecast row's delivery period plus the number of work days between periods entered for this forecast. If it is the first forecast row, the system will enter the period that equals today's date plus the number of work days between periods entered for this forecast.
By default the period has the format selected in the setting Date format for periods under the System tab in the Settings procedure. Via the Info menu, accessed by right-clicking, you can make a temporary choice of period format to be used; YYWW, YYWWD or Date.