Martin (1992: 367):
Because of the text's genre, recount rather than procedure, the realisation of activity sequences is more fragmented than in text [4:2];
In SFL theory, the rhetorical function of language is modelled as the system of mode, the textual dimension of context (Halliday & Matthiessen 1999: 321). Any function of language is more abstract than language, just as any function of form (e.g. Process) is more abstract than form (e.g. verbal group). The level of abstraction above language is context — and field, tenor and mode are its metafunctional dimensions. The relation between strata is realisation, which is an intensive identifying relation.
Genre, on the other hand, refers to a text type: a class to which a text belongs as a member. The relation between a text and its genre is thus class membership, which is an intensive attributive relation. In SFL theory, this relation is modelled as a cline of instantiation, with text at the instance pole, and text type, or register, midway between the instance and the system of overall potential. A text is a member (Carrier) of a register (Attribute), which is a member (Carrier) of a system (Attribute).