Martin (1992: 505):
The advantage of formulating genre as a pattern of register patterns will now be briefly reviewed:
This needs unpacking from several angles. (The 'pattern of patterns' formula is stratal realisation stated in terms of redundancy.)
From the perspective of SFL theory, genre is text type: it is register viewed from the instance pole of the cline of instantiation, just as register is text type viewed from the system pole of the cline of instantiation. From this perspective, Martin's formulation relates the same phenomenon viewed from different poles of the cline of instantiation as different levels of symbolic abstraction (strata).
However, from the perspective of SFL theory, Martin's 'register' corresponds to context. From this perspective, Martin's formulation relates text type and context as different levels of symbolic abstraction, such that text type is realised by context. That is, on this model, a type of language is realised by the culture as a semiotic system. On the SFL model, context is realised by language — the reverse of Martin's formulation.
A broader inconsistency here is the modelling of types (genre and register) as strata. In SFL theory, strata — context, semantics, lexicogrammar, phonology — are not types. Types are modelled in terms of instantiation, not stratification.