Sign languages, like spoken languages, organize elementary, meaningless units called phonemes into meaningful semantic units. (These were once called cheremes, from the Greek word for "hand", in the case of sign languages, by analogy to the phonemes, from Greek for "voice", of spoken languages, but now also called phonemes, since the function is the same.) This is often called duality of patterning. As in spoken languages, these meaningless units are represented as (combinations of) features, although crude distinctions are often also made in terms of handshape (or "handform"), orientation, location (or "place of articulation"), movement, and non-manual expression. More generally, both sign and spoken languages share the characteristics that linguists have found in all natural human languages, such as transitoriness, semanticity, arbitrariness, productivity, and cultural transmission.