Roland Barthes diagrams connotation such that on the level of the signifier, yet another sign (or set of signs) is stacked upon the initial signifying unit. According to Barthes, "a connoted system is a system whose plane of expression is itself constituted by a signifying system (Elements of Semiology 90)." The "expression" plane is constituted by material sound-images used as the signifier component in the total sign. On the other hand, the "content" plane is the continuum of mental thoughts and concepts, the signifieds, that are to be expressed. Barthes' model is useful in showing how a multiplicity of meanings can be evoked by a single word. He was dissatisfied by Saussure's model of the sign precisely because it didn't give fitting consideration to the possibility of a multiplied signifier. In this sense, Barthes would say that Saussure's model represents denotation proper.
--Image from Elements of Semiology