Various unclassified notes for the weird IBM midrange thing.
This is a weird “feature” of OV/400/side effect of not having a proper terminal keyboard. Press PF13 and set Adjust text when editing to N. As far as I can tell this doesn't really have any negative impact. A newline in OV/400 is expressed with the Carriage return macro, you'll have to bind this in your 5250 client. I use shift+enter.