Implement Field Exit within program

For this example I am using dta element 'EBELN' from table EKKO.

Step 1: 	Execute program ‘RSMODPRF’, entering the data element of the field
    

Step 2:	Create function module when prompted, and add you code to the source section using the parameter
	‘INPUT’ as the field value you are checking.
    
    

Step 3: 	Save and activate Function and execute transaction ‘CMOD’.

Step 4: 	Choose option: Goto-> Text Enhancements->Data elements->New DE cust docu.

Step 5: 	Enter data element
    
    

Step 6: 	Save and activate
Step 7: 	Execute program ‘RSMODPRF’ again but this time leave data element field blank.
Step 8: 	Select the checkbox for the data element you have just created and choose option: Field exit->Activate

This will now be active for all instances of this data element, but you can assign specific program and screen
combinations by pressing the ‘Assign prog./screen’ button. You can also change the code you entered in the field
exit function module by pressing the ‘Edit FM’ button.