The present grammar [functional grammar] has been able to be pushed fairly far, because of the way it is organized; in particular, because of two related characteristics: one that it uses a sparse rather than a dense model of grammatical structure (ranks, not immediate constituents;), the other that it is a ʻchoiceʼ grammar not a ʻchainʼ grammar (paradigmatic not syntagmatic in its conceptual organization). Putting these two together means that there is a round of choices and operations (as ʻsystem-structure cycleʼ) at each rank, with clause choices realized as clause structures, realized as phrase/group choices, realized as phrase/group structures and so on; and since there is a wealth of apparatus – it is an extravagant theory, not a parsimonious one – the higher rank choices in the grammar can essentially choices in meaning without the grammar thereby losing contact with the ground.
- Halliday (1985), a pag.XIX