Halliday & Matthiessen (2014: 452):
This basic pattern may be modified by the nature of the logico-semantic relationship, for example, ‘quote’ as a paratactic relation is clearly not symmetrical: ‘John says, quote: its raining’ cannot be reworded as ‘it’s raining, quote: John says’. But whenever it is logically possible, a given semantic relationship will be symmetrical and transitive in combination with parataxis but not in combination with hypotaxis.