The document discusses semiotic systems and linguistic signs. It explains that semiotic systems have two dimensions: a content or meaning dimension, and an expression or realization dimension. Linguistic signs are established by conventions and stand in opposition to other signs. The document then describes the syntagmatic axis as relating to sequences or chains, while the paradigmatic axis relates to oppositions or choices within a system. Finally, it explains that systemic functional linguistics captures both syntagmatic and paradigmatic relations, with theoretical priority given to paradigmatic relations.