On the BBC's Sunday Politics show in Scotland, Mr Swinney was asked whether it was reasonable to let EU nationals vote when 750,000 Scots living south of the border would not be able to vote in the referendum.
I would say that it's completely unreasonable if you're going to use the same rules as a Westminster election.
In a "westminster election", British citizens living overseas can vote for up to 15 years in the constituency they were registered in before leaving the UK.
I can still see a requirement for a massive registration process in which Scots around the world, who currently hold UK passports, notify their desire swap to a Scottish passport if the referendum results in succession. Only those should then get to vote in the referendum.