European Union Bill

I am sorry to interrupt my noble friend. We have recently had a great many debates on referendums and, for the first time ever, we have created a precedent whereby a referendum—that in relation to the AV Bill—will be mandatory. All previous referendums have been advisory, rather than mandatory. We also had a long debate on what the turnout needed to be, and so on. Could my noble friend tell us, in regard to this Bill, whether it is proposed that the referendum should be mandatory or advisory?