Most transnational languages in the modern period have a system of writing, and for most such languages a standard orthography has been developed, often based on a standard variety of the language, and thus exhibiting less dialect variation than the spoken language. Sometimes there may be variation in a language's orthography, as between American and British spelling in the case of English orthography. In some languages orthography is regulated by language academies, although for many languages (including English) there are no such authorities. Even in the latter languages, a significant amount of consensus arises naturally, although a maximum of consistency or standardization occurs only when prescriptively imposed according to style guides.