[skissane]

Spanish opponents of Catalan independence repeatedly use the argument "Our constitution doesn't allow a part of our country to become independent; but in that regard our constitution is no different from those of many other countries".

So the question of what other countries' constitutions allow is relevant to the debate.

And the comment I was initially responding to was suggesting that the UK could only allow Scotland the choice of independence because it has an unwritten constitution. Explaining how other country's written constitutions could allow grants of independence to parts of the country is a relevant response.