The FirstReq & PODate is updated immediately and reflect if there is pending quantity - a customer order or production order that is pending. 

The calculation is based on the following:

When the PODATE on the part (ART) is calculated, the value from CSV:PurchaseLeadTimeMarginDays is used. 
(CSV:PurchaseLeadTimeMarginDays = Number of days to be used in the calculation of ART.FirstReq that show in PUR).
If the FirsteREQ is defined, the PODate is calculated to:

FIRSTREQ minus STDLEADTIME from the main folder on the part (ART) minus the value added to the CSV 'PurchaseLeadTimeMarginDays'.


Deldate is the calculated delivery date.
Delivery date is calculated by the system based on the requested/confirmed date, the customers delivery claims and available stock. If the customer accepts to receive delivery of goods before the confirmed date, when this is possible, the DelDate will be equal to the request date (ReqDate). If the Customer does not want to receive delivery of goods before the confirmed date, the DelDate will be equal to Conf.