possible now for a minimum of nine EU member states to use enhanced co-operation, but this new framework has been used only once. A second proposal, a unified European patent, is nearing completion [as of December 2010] with only two countries (Italy and Spain) not participating. The idea of a multi-speed Europe has been revived because of the following initiatives: the eurozone, with 20 member states and two more in ERM II (Bulgaria and Denmark). Every EU member except Denmark has agreed by treaty to join, but many currently have no plans to do so. the Schengen Area, with 27 member states, 23 EU members and four non-EU members (Iceland, Liechtenstein, Norway, and Switzerland). It excludes four EU members (Bulgaria, Cyprus, Ireland, and Romania), all of which are legally obligated to join in the future except Ireland. other initiatives limited to some states, such as the European Defence initiative and Prüm Convention. Furthermore, important events were: the enlargement of the European Union to 28 member-states and in the forthcoming years other candidates (Turkey, Montenegro, North Macedonia, Serbia, Iceland, Ukraine) where new members initially don't join the Schengen area and the Eurozone for some time. the European Convention that led to the European Constitution that was signed in 2004 by the 25 Heads of State, but was not ratified by all national parliaments or assemblies and so failed. Later most of its provisions were adopted through the Treaty of Lisbon that included additional opt-outs for some states. differences of view between EU members on some foreign diplomatic and military issues. In a 2004 article The Economist compared the variances of Europe to a lake that has many deep parts (areas in which countries are similar) and many shallow parts (areas in which countries have major differences). Currently in the EU there are the following cases of non-uniform application of the European Union law: Overview of non-uniformity inside the EU Austria, Belgium, France, Germany, Luxembourg, and Slovenia participate in all EU provisions. Participation of European countries in non EU-only integration initiatives A number of countries have special relations to the European Union implementing many of its regulations. Prominently there are Norway, Iceland, Switzerland and Liechtenstein which are the only remaining EFTA members while all other former EFTA members have converted into EU members. Through agreements Norway, Iceland and Liechtenstein (not including Switzerland) are members of the European Economic Area since 1994. As