- Europe is taken here in its geographical meaning: north of the Mediterranean Sea, west of the Bosporus, north of the Caucasus and west of the Ural. Extra listed are countries cultural considered to be part of Europe: Cyprus, Armenia and Georgia. Russia and Turkey are only included for their European parts. Kazakhstan and Azerbaijan are - since they do not have a substantial European part - not included, but Artsakh is included.
- Included are independent recognized and non-recognized countries and semi-independent countries as well as overseas dependencies. Dependencies and colonies outside Europe are mentioned in the entries of the colonizing state. Non-recognized countries are included in the entry of the country they are legally part of. Exception is Artsakh, since Azerbaijan is not included.
- Each entry includes the entities that existed on the territory of the country, as far as they were itself more or less (de facto) independent entities. Not included are constituent, feudal and/or similar entities in countries.
- As far as Northern Italy was not a part of the Holy Roman Empire after 1648 as th the Peace of Westphalia effectively terminated any imperial claims to an Italian kingdom, the choice has been made not to include the tiny feudal states in Imperial Italy that existed until the Napoleonic era. A list can be found at Feudi Imperiali.
- Not included are partisan republics established as a predecessor of a future liberated country and entities that didn't have the objective to form an own country. They and contra-governments can be listed italic.
- Many of the colonies established by England (United Kingdom), France, the Netherlands, Portugal and Spain often change hands before they become a long-lasting dependency. These changes are generally not included. The legal status of overseas possessions can be various, from possession to protectorate.
- The scheme gives information on the development of political structures in a country. A difference has been made in estates assemblies, representing estates in a country, and parliaments, the latter seen as a representation of the population of a country. If a parliament is bicameral, independent of its name the upper house or chamber is labeled as senate. On suffrage a difference has been made between limited suffrage, based on limitations on income, profession, class, tax etc., universal male suffrage, giving (almost) all men above a certain age the right to vote, and universal suffrage, giving (almost) all women above a certain age the right to vote.