Martin (1992: 488):
In this chapter a brief sketch of some of the ways in which discourse semantics interacts with lexicogrammar and phonology has been presented. The problem addressed is a fundamental concern of modular models of semiosis — namely, once modules are distinguished, how do they interface? What is the nature of the conversation among components?
 In SFL theory, the relation between strata, such as semantics and lexicogrammar, is realisation, which is an intensive identifying relation. That is, strata are levels of symbolic abstraction, and as such, complementary perspectives. The notion that different levels of abstraction can interact derives from a misunderstanding of strata as modules.
 The chapter discussed a lexicogrammatical function (New information) realised by a phonological system (tonicity), rather than phonology itself. Moreover, New information — despite being misconstrued as phonology — was further misrepresented as an element of the clause (instead of the information unit).
 SFL theory is not a modular model of semiosis, and this misunderstanding is one source of the serious global theoretical errors in Martin's discourse semantic model.
Modules are distinct units that can be combined with others to make more complex structures. That is, a modular model is one whose organising principles are association and composition, which, in terms of expansion, are types of extension. The overarching organising principle of SFL theory, on the other hand, in terms of expansion, is elaboration. Elaboration is the organising principle of:
- systemic delicacy,
- stratification (along with identity),
- axial relations (along with identity),
- the cline of instantiation (along with ascription).
Extension is an organising principle of system network wiring (conjunctive 'and' and disjunctive 'or') and the rankscale of forms (composition).
In short, strata are not modules, not components, and the relation between them — realisation — is not one of extension, but one of elaboration and symbolic identity.