Was that intended? It seems a bit weird to have a field for communnicating that both parties can edit. Especially if this field is used for information that could be contested, like a due date.
Modifications submitted to the ILL end up in notesopac and over-write what is currently there. So if a user keyed data into the Notes field when the ILL was built, and then later submitted a modification, we would lose what had been in the opacnotes when they created the ILL.
I am not sure if it's a problem that it's editable for both, if the use case was defined clearly. This would also help as I feel that different backends might already use this differently?