Questions around nationhood, tax autonomy, international representation and policy powers are at the heart of Sunday's violence-marred independence referendum in Catalonia, Spain's wealthiest region.

This is how Catalonia compares with other regions with separatist leanings.

Catalonia

Nationhood

A historic principality that became part of a united Spanish kingdom in the 15th century, it is one of 17 autonomous regions under Spain's devolved political system created after the death of dictator Francisco Franco in 1975. It has its own government, presidency, and parliament. The statute of autonomy defining Catalonia's powers refers to Catalonia as a “nationality”.

Catalan and Spanish share status as official languages in Catalonia. Catalonia has its own flag and anthem.

Tax autonomy

Half of the income tax and value-added tax (VAT) levied in Catalonia is returned to the region of 7.5 million people, with the central government in Madrid deciding how the rest is spent. Company taxes also go to Madrid.

Catalonia receives 58 per cent of the proceeds of a number of other taxes, including on alcohol and fuel, raised there. Its tax-collecting agency also gathers some taxes on wealth, inheritance, gambling and transport and keeps all the proceeds.

Catalonia, with about 16 perc ent of Spain's population of 47 million, complains about the redistribution of tax revenues.

Each year, it pays about 10 billion euros ($12 billion) more in taxes to Madrid than it gets back, or around 5 per cent of regional economic output, according to Spanish Treasury data.

International representation

The Catalan government has a number of delegations abroad, including in Brussels, London and Washington.

Policy powers

The Catalan government has broad powers in areas such as education, health, security, culture, urban development and the environment. It has its own police force, the Mossos d'Esquadra.

The central government has powers over foreign, defence, immigration and broad economic policy.

Scotland

Nationhood

A kingdom occupying the northern half of the island of Great Britain from the 9th century, Scotland's monarch took the crown of England through dynastic succession in 1603 and in 1707 the two countries formed the state of Great Britain. It is now part of the United Kingdom, with England, Wales and Northern Ireland.

Tax autonomy

After rejecting independence in a 2014 referendum, Scotland was allowed to raise a portion of its own taxes with the option to set what is currently half the level of income tax.

From this year, it has had the power to set rates and bands of income tax, and half of VAT receipts from Scotland are now assigned to the Scottish government to spend.

The rest of Scotland's financing comes from the UK budget via a formula which takes into account population changes. In general, Scotland, with about 8 per cent of the UK's 66 million population, is a net beneficiary from the central budget.

International representation

Scotland has its own international soccer team and the Scottish government has offices in Brussels, Washington, Toronto and Beijing to promote its regional interests.

Scottish Development International also has some 40 offices in about 20 countries aimed at promoting trade and investment.

Policy powers

Decisions taken in Scotland's parliament at Holyrood in Edinburgh, which was created in 1999, encompass agriculture, health, education, transport, local government, law, social work, housing, tourism and economic development, sport and arts.

All other powers â such as immigration, defence and foreign policy - are reserved to the UK parliament at Westminster.

Flanders

Nationhood

After gaining independence from the Netherlands in 1830, Belgium later faced demands for equality from Dutch-speakers in a state dominated by the then-richer French-speaking south. Since the Second World War, demands for independence for the now more numerous and richer Flemings were met with six rounds of constitutional change that left Dutch-speaking Flanders and French-speaking Wallonia highly autonomous within a complex federal structure.

Tax autonomy

Most tax rates are set at federal level, though the regions have some powers, such as over car and property taxes. In general, Flanders with about 6 million of Belgium's 11 million people, is a net contributor to the federal budget.

International representation

Regional governments are in charge of foreign trade and conduct separate trade missions in addition to those of the federal government. Wallonia nearly derailed an EU-Canada trade deal last year. Flanders has permanent representatives in several locations Europe, as well as New York and Pretoria.

Policy powers

Flanders, like Wallonia, is in charge of several policy areas, notably education, healthcare and agriculture.

Catalonia independence referendum: Riot police clash with voters Show all 17 1 /17 Catalonia independence referendum: Riot police clash with voters Catalonia independence referendum: Riot police clash with voters A man faces off Spanish Civil Guards outside a polling station in Sant Julia de Ramis Reuters Catalonia independence referendum: Riot police clash with voters Riot police form a security cordon around the Ramon Llull school in Barcelona EPA Catalonia independence referendum: Riot police clash with voters Riot police evict a young woman during clashes between people gathered outside the Ramon Llull school in Barcelona EPA Catalonia independence referendum: Riot police clash with voters Spanish Civil Guard officers break through a door at a polling station in Sant Julia de Ramis Reuters Catalonia independence referendum: Riot police clash with voters Spanish National Police clash with pro-referendum supporters in Barcelona on Sunday AP Catalonia independence referendum: Riot police clash with voters Crowds raise their arms up as police move in on members of the public gathered outside to prevent them from voting in the referendum at a polling station where the President Carles Puigdemunt will vote later today Getty Catalonia independence referendum: Riot police clash with voters People confront Spanish Civil Guard officers outside a polling station Reuters Catalonia independence referendum: Riot police clash with voters Three man hold each other as they try to block a Spanish police van from approaching a polling station AP Catalonia independence referendum: Riot police clash with voters A woman shows a ballot to a Spanish Civil Guard officer outside a polling station Reuters Catalonia independence referendum: Riot police clash with voters A man wearing a shirt with an Estelada (Catalan separatist flag) and holding carnations faces off with a Spanish Civil Guard officer Reuters Catalonia independence referendum: Riot police clash with voters Police try to control the area as people attempt to cast their ballot at a polling station in Barcelona Getty Catalonia independence referendum: Riot police clash with voters A man is grabbed by officers as police move in on the crowds Catalonia independence referendum: Riot police clash with voters Two women argue with a Spanish National policeman during clashes between Catalan pro-independence people and police forces at the Sant Julia de Ramis sports centre in Girona EPA Catalonia independence referendum: Riot police clash with voters Sant Julia De Ramis in Spain Getty Catalonia independence referendum: Riot police clash with voters Confrontation outside a polling station in Barcelona, where police have tried to stop people voting AFP/Getty Images Catalonia independence referendum: Riot police clash with voters A Spanish National Police officer aims a rubber-bullet rifle at pro-referendum supporters in Barcelona AP Catalonia independence referendum: Riot police clash with voters Riot police clashed with voters as polls opened in Barcelona Sky News

Quebec

Nationhood

Mainly French-speaking since the days of British and French colonial rivalry in North America, Quebec, with a population of 8.2 million, is now one of 10 provinces of the federal state of Canada, whose population is 36 million.

Independence referendums in 1980 and 1995 delivered majority votes in favour of remaining part of Canada. The Canadian parliament voted in 2006 to recognise Quebec as a “nation”.

Tax autonomy

All Canadian provinces have the power to levy provincial taxes and receive transfer payments from the federal government.

International representation

Quebec, has its own delegations in the Unites States, Latin America, Asia, Europe and Africa. Quebec is also a member of its own right in some international organisations, including UNESCO, the UN education, science and culture arm.

Policy powers

The province can make laws concerning provincial matters and is still bound by federal regulations.