Deaf education
It is unknown when the first attempts were made to represent an oral language with gesture. Indeed, some have speculated that oral languages may have evolved from sign languages, and there may be undocumented cases in history when vocal and signed modes of a language existed side by side. It is not uncommon for people to develop gestures to replace words or phrases in contexts where speech is not possible or not permitted, such as in a television studio, but these are usually limited in scope and rarely develop into complete representations of an oral language. One of the most elaborated examples of this kind of auxiliary manual system is Warlpiri Sign Language, a complete signed mode of spoken Warlpiri which was developed by an Indigenous community in central Australia due to cultural proscriptions against speech. Sign language linguists usually make a distinction between these auxiliary sign languages and manually coded languages; the latter are specifically designed for use in Deaf education, and usually represent the written form of the language.