West Berlin as their place of residence. However, West Berliners could not use their passports for crossing East German borders and were denied entrance by any country of the Eastern Bloc, since governments of these countries held the view that West Germany was not authorized to issue legal papers for West Berliners. Since West Berlin was not a sovereign state, it did not issue passports. Instead, West Berliners were issued with "auxiliary identity cards" by the West Berlin authorities. These differed visually from the regular West German identity cards, with green bindings instead of the grey standard, they did not show the "Federal Eagle" or coat of arms, and contained no indications as to the issuing State. However, they did have a statement that the holder of the document was a German citizen. From 11 June 1968, East Germany made it mandatory that West Berlin and West German "transit passengers" obtain a transit visa, issued upon entering East Germany, because under its second constitution East Germany considered West Germans and West Berliners foreigners. Since identity cards had no pages to stamp visas, issuers of East German visas stamped their visas onto separate leaflets which were loosely stuck into the identity cards, which, until the mid-1980s, were little booklets. Although the West German government subsidized visa fees, they were still payable by individual travellers. In order to enter visa-requiring Western countries, such as the US, West Berliners commonly used West German passports. However, for countries which did not require stamped visas for entry, including Switzerland, Austria, and many members of the then European Economic Community, including the United Kingdom, West Berlin identity cards were also acceptable for entry. Active immigration and asylum politics in West Berlin triggered waves of immigration in the 1960s and 1970s. As of 2017, Berlin was home to at least 178,000 Turkish and Turkish German residents, making it the largest Turkish community outside of Turkey. West Berlin was also a destination for many people fleeing East Germany both before and after the construction of the Berlin Wall. As many immigrants from East Germany did not intend to stay in Berlin, flights - the only option for those people to reach West Germany without coming into contact with East German authorities - were subsidized by the West German government despite being operated only by companies registered in and owned by nationals of the western occupying powers. Naming conventions