Question: What is the agreement allowing free movement between northern European countries including Finland, Sweden and Denmark?

Context articles: Space Crusade
Crash and Burn (Savage Garden song)
Segmentation (biology)
Finland–Sweden border
Open border
Nordic Passport Union
Citizens’ Rights Directive
Comparing Media Systems
Paf (company)
Slack action

Space Crusade is an adventure board game produced by Milton Bradley together with Games Workshop and was first made in 1990.
 While produced in the UK and available in some other countries including Finland, Ireland, France, Spain, Denmark, Australia and New Zealand, it was never sold in North America.
 In Germany, Italy, Belgium and the Netherlands, it is known as Star Quest.
"Crash and Burn" is a song by Australian pop group Savage Garden from their second album "Affirmation", released as the album's third single in the beginning of 2000.
 It hit number one in several countries including Finland and Norway, and it reached the top five in Australia, New Zealand, Canada, Sweden and France among others.
Segmentation in biology is the division of some animal and plant body plans into a series of repetitive segments.
 This article focuses on the segmentation of animal body plans, specifically using the examples of the taxa Arthropoda, Chordata, and Annelida.
 These three groups form segments by using a “growth zone” to direct and define the segments.
 While all three have a generally segmented body plan and use a “growth zone,” they use different mechanisms for generating this patterning.
 Even within these groups, different organisms have different mechanisms for segmenting the body.
 Segmentation of the body plan is important for allowing free movement and development of certain body parts.
 It also allows for regeneration in specific individuals.
The Finnish-Swedish border is the border between the countries of Finland and Sweden.
 Almost the entire border runs through water: along the Tornio River and its tributaries, and in the Gulf of Bothnia.
 Only a few kilometres of the border are on dry land.
 Because of the Schengen treaty and the Nordic Passport Union, the border can be crossed mostly freely.
An open border is a border that enables free movement of people between different jurisdictions with limited or no restrictions on movement, that is to say lacking substantive border control.
 A border may be an open border due to a lack of legal controls or intentional legislation allowing free movement of people across the border ("de jure"), or a border may be an open border due to lack of adequate enforcement or adequate supervision of the border ("de facto").
 An example of the former is the Schengen Agreement between most members of the European Economic Area (EFTA and the EU).
 An example of the latter has been the border between Bangladesh and India, which is becoming controlled.
 The term "open borders" applies only to the flow of people, not the flow of goods and services, and only to borders between political jurisdictions, not to mere boundaries of privately owned property.
The Nordic Passport Union allows citizens of the Nordic countriesIceland, Denmark, Norway, Sweden, and Finlandto travel and reside in another Nordic country (excluding Greenland and Svalbard) without any travel documentation (e.g. a passport or national identity card) or a residence permit.
 Since 25 March 2001, all five states have also been within the Schengen Area.
 The Faroe Islands are part of the Nordic Passport Union but not the Schengen Area, while Greenland and Svalbard are outside both.
The Citizens’ Rights Directive 2004/38/EC (also sometimes called the "Free Movement Directive") defines the right of free movement for citizens of the European Economic Area (EEA), which includes the member states of the European Union (EU) and the three European Free Trade Association (EFTA) members Iceland, Norway and Liechtenstein.
 Switzerland, which is a member of EFTA but not of the EEA, is not bound by the Directive but rather has a separate bilateral agreement on free movement with the EU.
Comparing Media Systems: Three Models of Media and Politics (2004), by Daniel C. Hallin and Paolo Mancini, is a seminal study in the field of international comparative media system research.
 The study compares media systems of 18 Western democracies including nine Northern European countries (Austria, Belgium, Denmark, Finland, Germany, the Netherlands, Norway, Sweden, and Switzerland), five Southern European countries (France, Greece, Italy, Portugal, and Spain) and four Atlantic countries (Canada, Great Britain, Ireland, and the United States).
Ålands Penningautomatförening or Paf is a Finnish company that operates a legal gambling monopoly on the Åland Islands, Finland.
 Paf also has an Internet-based gambling and gaming operation, in addition to operating and maintaining casino and gaming activities on a large number of cruise ferries.
 The purpose of Paf is to generate funds for humanitarian and social causes on the Åland Islands.
 Paf serves players from countries including Finland, Sweden, Estonia, Spain and Italy.
 Paf is licensed and controlled by the local Åland government.
In railroading, slack action is the amount of free movement of one car before it transmits its motion to an adjoining coupled car.
 This free movement results from the fact that in railroad practice cars are loosely coupled, and the coupling is often combined with a shock-absorbing device, a "draft gear," which, under stress, substantially increases the free movement as the train is started or stopped.
 Loose coupling is necessary to enable the train to bend around curves and is an aid in starting heavy trains, since the application of the locomotive power to the train operates on each car in the train successively, and the power is thus utilized to start only one car at a time.