>I open my database exclusively, but when I try to edit the referential integrity, I get a message saying that the database is not opened exclusively and ri code cannot be generated. I set exclusive on in the command window, but no luck.

IIRC it's an old bug, which may have been fixed in the latter versions (namely, Chen's) but it's obscure enough so I think it's not.

You have to have set exclusive on before you do anything. So quit fox, reload it, set exclusive on, open database exclusively and do what you want. In that order.