[...] we would rule out, as non-language, systems which use other than vocal sign vehicles; systems whose sign-vehicles are not composed of discrete recurring units (phonemes); systems which have unrestricted combinability of signs (i.e. no grammar); systems whose signs are iconic; perhaps even such systems ― to add a pragmatic criterion ― as are not used for interpersonal communication.
- Weinreich (1963), a pag.114