Manually coded languages (MCLs) are a family of gestural communication methods which include gestural spelling as well as constructed languages which directly interpolate the grammar and syntax of oral languages in a gestural-visual form—that is, signed versions of oral languages. Unlike the sign languages that have evolved naturally in deaf communities, these manual codes are the conscious invention of deaf and hearing educators, and as such lack the distinct spatial structures present in native deaf sign languages. MCLs mostly follow the grammar of the oral language—or, more precisely, of the written form of the oral language that they interpolate. 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.