There is an age-old distinction between dyadic and triadic sign models in semiotics. Most of dyadic sign models describe the relationship between the meaning and the carrier of that meaning (e.g. the relationship between content and form or signified and signifier). A classical example of the dyadic sign model is the model of the linguistic unit introduced by Swiss linguist and semiotician Ferdinand de Saussure . Triadic sign models add a third component to the sign—an external referent in relation to which the sign has its meaning. In the semiotic tradition stemming from the works of Charles S. Peirce , this aspect of the sign is called the "object" and the triadic sign, correspondingly, consists in the relationship between the representamen, the object and the interpretant.