Sign languages vary across the world
Of course, we talk about “Sign Languages” in plural because there are a lot of them and, in fact, it is very likely that we have not identified all of them yet. The best known of them are those that belong to some country or state with a numerically important community of users. Nevertheless, we also know cases of rural Sign Languages in several points of the planet that have sprung in small communities that have developed their own Sign Language. The one thing that is clear is that, although there are some similarities that derive from visual-gestural modality, all Sign Languages have grammars and lexicons of their own, and that they are not by any means a gestural version of the Spoken Languages in their environment. That is why we speak of Catalan Sign Language in the sense that it is the sign language belonging to Catalonia, and not of Signed Catalan, as some people might still wrongly say.