When should I use OVRDTA and PUTOVR in a designing a Display Screen? (DSPF)
The PUTOVR keyword is used to modify the data stream being sent to a display device. On the first write to a record format the PUTOVR keyword is ignored. It is also ignored if there are no fields (Input or I/O) with the OVRDTA or OVRATR active. On subsequent writes, only changed or modified data is sent to the display. If you are overlaying another record format such as a command key format for a subfiles, you can use the PUTOVR and OVRDTA and/or OVRATR to force a change to a the data displayed in an I/O field or it's attributes. If you are using the display attribute ND (Non-Display), you would need to use the OVRATR to force the field to appear or disappear, especially if it overlaps another field. There are examples in the AS/400 library.