How to configure and work with IDOC field changes on AIF ?
If your AIF interface is already created you just need to add the field you need to change in transaction Transaction - /AIF/CUST_IF - Error Handling - Interface Specific Features - in this case this will be the program name field - REPIO from the main segment - E1STATS.
Once the configuration is complete you can go to Error Handling and Monitoring transaction - /AIF/ERR and open the relevant segment and field as shown in the Figure below.
As soon as you change the field you need to save the changes.
Then you can reprocess the message in AIF - by selecting it and restarting from the menu.
The updated message will get processed and in WE02/WE05 you will see the old IDOC (green status) and the updated one with new field so AIF is working in the same way as the normal IDOC field update.
Updating IDOC fields is nothing new but this article shows that you can do the same with AIF and it works in the same way as it used to with IDOC transactions only.