Diasystem

In linguistics, a diasystem is a term used in structural dialectology, to refer to a single genetic language which has two or more standard forms. The dialects are often divided into separate languages due to political reasons, most obviously with Serbo-Croatian, which is split into Bosnian, Croatian and Serbian due to their use by different Slavic groups in the Balkans and their status in the nations of Bosnia and Herzegovina, Croatia and Serbia respectively. Other possible differences between languages include vocabulary, such as Occitan being affected by French and Catalan by Spanish words, and writing systems, such as Hindi in Devanagari and Urdu in the Arabic script, despite being mutually intelligible.