West European scientists judge the Yugoslav language policy as an exemplary one: although three-quarters of the population spoke one language, no single language was official on a federal level. Official languages were declared only at the level of constituent republics and provinces, and very generously: Vojvodina had five (among them Slovak and Romanian, spoken by 0.5 per cent of the population), and Kosovo four (Albanian, Turkish, Romany and Serbo-Croatian). Newspapers, radio and television studios used sixteen languages, fourteen were used as languages of tuition in schools, and nine at universities. Only the Yugoslav Army used Serbo-Croatian as the sole language of command, with all other languages represented in the army’s other activities—however, this is not different from other armies of multilingual states, or in other specific institutions, such as international air traffic control where English is used worldwide. All variants of Serbo-Croatian were used in state administration and republican and federal institutions. Both Serbian and Croatian variants were represented in respectively different grammar books, dictionaries, school textbooks and in books known as pravopis (which detail spelling rules). Serbo-Croatian was a kind of soft standardisation. However, legal equality could not dampen the prestige Serbo-Croatian had: since it was the language of three quarters of the population, it functioned as an unofficial lingua franca. And within Serbo-Croatian, the Serbian variant, with twice as many speakers as the Croatian, enjoyed greater prestige, reinforced by the fact that Slovene and Macedonian speakers preferred it to the Croatian variant because their languages are also Ekavian. This is a common situation in other pluricentric languages, e.g. the variants of German differ according to their prestige, the variants of Portuguese too. Moreover, all languages differ in terms of prestige: "the fact is that languages (in terms of prestige, learnability etc.) are not equal, and the law cannot make them equal".