Brexit: The UK's future in the European Economic Area (EEA)
Most people will have heard about Article 50 - triggered by Theresa May in March formally starting the Brexit process - but there is now talk about Article 127, which some think needs a starting gun too.
As well as being a member of the EU, the UK is part of the European Economic Area (EEA), signed by countries within the single market, as Daily Politics presenter Jo Coburn explains.
Watch the studio debate about Article 127 with MPs Kwasi Kwarteng and Heidi Alexander