Martin (1992: 168):
… in spontaneous spoken monologue the semantic system of CONJUNCTION tends to be realised through paratactic and hypotactic relationships within the clause complex, and through 'cohesive' conjunctions relating clause complexes to each other. Texts produced in this way foreground realisations of CONJUNCTION as logico-semantic relationships between processes.
 This creates a metafunctional inconsistency at the level of semantics by merging systems of the logical metafunction: logico-semantic relations and taxis, with systems of the textual metafunction: cohesive conjunction.
 Relations between clauses in complexes involve two distinct simultaneous systems: the LOGICO-SEMANTIC TYPE: projection or expansion, and the degree of INTERDEPENDENCY or TAXIS: hypotaxis or parataxis (Halliday & Matthiessen 2004: 373). Logico-semantic relations are not "realised through" tactic relations.