Scottish independence: In or out of Europe. A simple question?
The question is deceptively simple - would an independent Scotland remain a member of the European Union?
Finding a definitive answer is proving rather trickier.
The European Commission (EC) insists that any "new state" would have to apply to become a member of the 27-country club.
But would Scotland be regarded as a new state if its people voted for independence?
The Scottish National Party, which runs the devolved government in Edinburgh, argues not.
It points out that Scotland was an independent nation before its union with England in 1707 and insists that five million Scots would have as much right to remain as citizens of the EU as their 58 million neighbours in England, Wales and Northern Ireland.
Both Scotland and the remainder of the UK would be regarded as "successor states", says the SNP, not new members.
The EC refuses to comment publicly on the specifics of Scotland's case, but the mood music from Brussels must sound discordant to SNP ears.
On 12 September on BBC Radio 4's The World at One, the EC president Jose Manuel Barroso was asked whether an independent Scotland would have to reapply to join the EU.
Mr Barroso said he would not speculate on possible secessions.
But he added: "It is a procedure of international law. A state has to be a democracy first of all and that state has to apply to become a member of the European Union and all the other member states have to give their consent.
"A new state, if it wants to join the European Union, has to apply to become a member of the European Union like any state."
Today, following reports in the Scotsman, an EC official told the BBC that an independent Scotland would have to reapply for membership.
But that is where it becomes more complicated.
The Scottish government insists that it wouldn't actually be independent when the negotiations were taking place and so it would not have to reapply.
Ministers in Edinburgh say that, in the event of a yes vote, Edinburgh would negotiate the terms of its independence with London between 2014 and 2016.
They argue that during that period, while Scotland remained part of the UK and the UK remained part of the EU, they would be able to negotiate their terms of EU membership "from within".
They suggest that the UK government would support this process, not least because the Edinburgh Agreement, which set out the framework for the referendum, commits both parties to respect the outcome and work together in the best interests of the people of both Scotland and the rest of the UK.
It would clearly be in everyone's interests, they argue, for everyone to remain inside the EU.
Leaving aside the assumption about EU membership being a good thing, it is still not clear whether Brussels would accept negotiations on that basis.
One thing might make the position clearer.
EU member request
It is not clear whether Mr Barroso's comments reflect his personal political position or the EC's formal legal position.
The EC refuses to publish its legal advice on an independent Scotland's potential membership, saying it will only do so if it receives a request from a European Union member.
That would mean the UK government, which refuses to make such a request, saying it has no need to consider how Scottish independence, which it opposes, would work.
Perhaps more strangely the Scottish government has refused even to lobby Whitehall to ask Brussels for the advice.
The position of all three institutions is arguably keeping Scottish voters in the dark.