Martin (1992: 569):
There are many avenues for extending a network of this kind [classifying story genres]. Recounts, for example, can be subclassified with respect to the time scale involved (my day, last week-end, it's been quite a month, annual reports, biographies, history etc.). Cross-classifying +/– frustration with reaction/judgements makes room for fables (+frustration/+judgement), parables and other moral tales. Anecdotes need to be related to jokes, and possibly comedy of various kinds. And narrative, needless to say, has to be indefinitely extended if it is to do justice to the centuries of composing and research that has elaborated such a significant portion of our culture. Of this work, English Text has offered the barest glimpse.
 To be clear, from an SFL perspective, this is classifying text types (genres) "from roundabout", in terms of their semantics, instead of "from above", in terms of the the cultural (contextual) functions they serve. As a functional theory, SFL gives priority to the view "from above".
From Martin's perspective, where genre and register are misconceived, not as language, but as strata of context, this is classifying genres "from below" — from the second stratum below, discourse semantics, leapfrogging register.
 This is true.