Question: What was the planned, first devised by Raivis Zeltits, to form a federation of Central and Eastern European countries after World War I?

Context paragraphs:
Flight and expulsion of Germans (1944–50): During the later stages of World War II and the post-war period, German citizens and people of German ancestry were expelled from various Eastern European countries and sent to the remaining territory of Germany and Austria.  After 1950, some emigrated to the United States, Australia, and other countries from there.  The areas affected included the former eastern territories of Germany, which were annexed by Poland and the Soviet Union after the war, as well as Germans who were living within the prewar borders of Poland, Czechoslovakia, Hungary, Romania, Yugoslavia, and the Baltic States.  The Nazis had made plans—only partially completed before the Nazi defeat—to remove many Slavic and Jewish people from Eastern Europe and settle the area with Germans.  The post war expulsion of the Germans formed a major part of the geopolitical and ethnic reconfiguration of Eastern Europe in the aftermath of World War II, that attempted to create ethnically homogeneous nations within redefined borders.  Between 1944 and 1948 about 31 million people, including ethnic Germans ('Volksdeutsche') as well as German citizens ('Reichsdeutsche'), were permanently or temporarily moved from Central and Eastern Europe.

Tyer's Electric Train Tablet: Tyer's Electric Train Tablet system is a form of railway signalling for single line railways used in several countries; it was first devised in Great Britain by engineer after the Thorpe rail accident of 1874, which left 21 people dead.  It was used in New Zealand for close to 100 years until June 1994.

City of London Pedway Scheme: The City of London Pedway Scheme is a partial elevated pedway that evolved out of a plan to transform traffic flows in the City of London by separating pedestrians from street level traffic using elevated walkways.  First devised as part of the post World War II reconstruction plans for London, it was put into effect mainly from the mid-1950s to the mid-1960s and eventually abandoned by the 1980s.

Canadian Forces Language School: The Canadian Forces Language School (CFLS) is an institution of the Canadian Forces responsible for providing language education.  The CFLS has its headquarters in Gatineau, Quebec, along with its National Capital Region Training Company, and detachments at Saint-Jean-sur-Richelieu, Quebec, and Borden, Ontario.  Since 1993, CFLS Detachment Borden, located at Bldg P 153, has been teaching English as a Foreign Language to military officers from Central and Eastern European countries and Far East Countries.  Currently, 17 European and 2 Far Eastern countries are represented at the school.

List of International Mathematical Olympiads: The first of the International Mathematical Olympiads (IMOs) was held in Romania in 1959.  The oldest of the International Science Olympiads, the IMO has since been held annually, except in 1980.  That year the competition initially planned to hold in Mongolia was canceled due to soviet invasion of Afghanistan.  Because the competition was initially founded for Eastern European countries participating in the Warsaw Pact, under the influence of the Eastern Bloc, the earlier IMOs were hosted only in Eastern European countries, gradually spreading to other nations.  Sources differ about the cities hosting some of the early IMOs and the exact dates when they took place.

European Cultural Month: European Cultural Month is an event created by the European Union to promote culture.  It is similar to the European City of Culture, but lasting for a shorter time and intended mainly for the Central and Eastern European countries.  It was launched in 1990.

Raivis Zeltīts: Raivis Zeltīts (born 21 March 1992 in Riga) is a Latvian politician, national-conservative activist, and writer.  He is the Secretary General of the National Alliance, as well as board member and leader of its youth organization.  He was elected to the Marupe municipal council in the 2013 municipal elections and re-elected in 2017.  Has bachelor's degree in history.  He is the author of many articles both in Latvian and English about nationalism, geopolitics, and the idea of Intermarium in today’s Europe.  Liberal news magazine “New Eastern Europe” has called Raivis Zeltits “a key promoter of "identitaire" ideology in Latvian politics” and writes that with the national-conservative news portal “The New Nationalism” “Zeltīts has created a political platform, linking the far right from the Baltic to the Black Sea”.  On the 23d of August 2017 Zeltīts' first book “Par Nacionālu Valsti” (“On Nation State”) was published.  It describes the ideas and tasks of Latvian nationalism in the 21st century in a systematic way .

Satellite state: The term satellite state designates a country that is formally independent in the world, but under heavy political, economic and military influence or control from another country.  The term was coined by analogy to planetary objects orbiting a larger object, such as smaller moons revolving around larger planets, and is used mainly to refer to Central and Eastern European countries of the Warsaw Pact during the Cold War or to Mongolia between 1924 and 1990, for example.  As used for Central and Eastern European countries it implies that the countries in question were "satellites" under the hegemony of the Soviet Union.  In some contexts it also refers to other countries in the Soviet sphere of influence during the Cold War—such as North Korea (especially in the years surrounding the Korean War of 1950–1953) and Cuba (particularly after it joined the Comecon in 1972).  In Western usage, the term has seldom been applied to states other than those in the Soviet orbit.  In Soviet usage, the term applied to the states in the orbit of Nazi Germany and Fascist Italy.

HBO Europe: HBO Europe is a premium pay television service operating in 3 Central European Countries: Czech Republic, Slovakia, Hungary and also 11 Eastern European countries: Poland, Romania, Bulgaria, Slovenia, Kosovo, Bosnia and Herzegovina, Croatia, Moldova, Macedonia, Montenegro and Serbia.

Intermarium: Międzymorze (] ), known in English as Intermarium, was a plan, pursued after World War I by Polish leader Józef Piłsudski, for a federation, of Central and Eastern European countries.  Invited to join the proposed federation were the Baltic states (Lithuania, Latvia, Estonia), Finland, Belarus, Ukraine, Hungary, Romania, Yugoslavia and Czechoslovakia.

Supporting paragraphs: Raivis Zeltīts Intermarium
Answer: Intermarium