Manually coded

Manually coded languages are not themselves languages but are representations of oral languages in a gestural-visual form; that is, signed versions of oral languages (signed languages). Unlike the sign languages that have evolved naturally in Deaf communities, which have distinct spatial structures, these manual codes (MCL) are the conscious invention of deaf and hearing educators, and mostly follow the grammar of the oral language—or, more precisely, of the written form of the oral language. They have been mainly used in deaf education in an effort to "represent English on the hands" and by sign language interpreters in K-12 schools, although they have had some influence on Deaf sign languages where their implementation was widespread.

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.

In seventh century England, Bede, a Benedictine monk, proposed a system for representing the letters of the Latin script on the fingers. Monastic sign languages used throughout medieval Europe used manual alphabets as well as signs, and were capable of representing a written language, if one had enough patience. Aside from the commonly understood rationale of observing "vows of silence", they also served as mnemonics (memory aids) for preachers. These manual alphabets began to be used to teach the deaf children of royalty in 17th century Spain, and can be seen as a kind of proto-manually coded language. Such alphabets are in widespread use today by signing deaf communities for representing words or phrases of the oral language used in their part of the world.

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