Screen exits add fields to screens in R/3 applications. SAP creates screen exits by placing special subscreen areas on a standard R/3 screen and calling a customer subscreen from the standard screens flow logic.
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1.From the main screen of the Project management transaction, proceed as follows:
Select Enhancement components and choose Change.
2.Choose Edit component.
3.Choose the screen exit and double click on it
4.Create your subscreen using the Screen Painter.
5.Design your screen to be added to the standard screen and activate the particular screen and return back to the flow logic .
6.Choose the PAI and PBO to write down the logic.
7.Generate your screen and choose Back (the green arrow) to return to the Project management transaction.
8.Go to the transaction ME22 to view the customer defined screen exit.
9.Enter the purchase order number and press Enter.
10.Go to the menu header --> Details.
11.Purchase number is visible on the standard screen