Before revision: In spoken languages, they can give extra information but are not necessary for the receiver to understand the meaning of the utterance (for example, an autistic person may not use any facial expressions but still get their meaning across clearly, and people with visual impairements may understand spoken utterances without the need for visual aides).
After revision: In spoken languages, they can give extra information but are not necessary for the receiver to understand the meaning of the utterance (for example, an autistic person may not use any facial expressions but still get their meaning across clearly, and people with visual impairments may understand spoken utterances without the need for visual aides).