A linguistic sign is an abstract structure whose instances participate in a linguistic system, or language. By definition, a linguistic sign must have a form component (whose elements are phonological units), a grammatical component (whose elements are grammatical units), and a meaning component (whose elements are semantic units). The formal structure of a linguistic sign is determined by the grammar of a language. The information value of a linguistic sign, its meaning, is not fixed, but determined by the conventions of the language. The relation of form to meaning is largely arbitrary within a semiotic system. Signs are classified primarily according to what kinds of formal relations they participate in, and, secondly, according to their complexity (whether they are atomic or composed of other signs). Signs range from morphological and syntactic constructions to whole discourse segments [de Saussure 1983; Hervey 1979; Pollard and Sag 1994].