A - Before answering this question, we need to give you some background information. The highlighted area in the above sample screen can either display "Ship Date" (default behavior) or "ETA Date." This depends on the Global Setup -> PO Global Control. "12. Is PO Request and Promise Date The Arrival Date?" See sample screen below.
The default value for this flag is "Y," which means the PO Line Item Request or Promise Date is the date we on which we expect the merchandise to arrive at our company. Our ATP (Available To Promise) will be based on this date to show the expected receiving date in order to project future inventory balances.
While this date is very important for our own internal control, many users express the need to have a Ship Date ( i.e., the date the vendor should ship the line item in order to arrive at our company on the request or promise date). To support this, we added a "Shipping Lead Time" field in the vendor file maintenance. See sample screen below.
This vendor shipping lead time becomes the default PO Shipping Lead Time. See sample screen below.
Then, when you enter a PO Line Item, the "Ship Date" field is calculated as:
Ship Date = Line Request/Promise Date - PO Header Shipping Lead Time
So as you can see, you can't really edit the "Ship Date" in the PO Line Item screen. You can indirectly determine the "Ship Date" by changing the "20. Ship L-Time" in the PO Header or the Line Item Request/Promise Date. Just as a side note, if there's no promise date, then the request date is used. If there's a promise date, then the promise date overrides the request date.
Some users would rather use the Request/Promise Date in the PO Line Item screen to represent the "Ship Date." In that case, you will set up the Global Setup flag "12. Is PO Request and Promise Date The Arrival Date?" value as "N." In this scenario, instead of displaying "Ship Date," we display the "ETA Date." ETA stands for "Estimated Time of Arrival." See sample screen below.
The ETA Date is calculated as:
ETA Date = Line Request/Promise Date + PO Header Shipping Lead Time
On the Purchase Order Form Setup, you can select and print both Ship Date and ETA Date on the PO form. However, throughout most areas in the PO module, we only display the Request/Promise Date. So you should consider carefully which date should be your primary PO line item -- the Ship Date or the ETA Date. As mentioned before, the PO Line Item Request/Promise Date, by default, is considered as the ETA Date.