Halliday & Matthiessen (2014: 470):
Finally, before we leave elaboration, we should note examples that include asides:
||| For me, by the time I come to the end of a particular form || —The Greenlanders is an epic || and A Thousand Acres is a tragedy – || I am not all that pleased anymore with [[ what I got from it]] || and I’m fed up with [[ what I had to give up]] . |||Such asides may be analysed as clauses or clause complexes that are enclosed within a clause complex but which are not part of the structure of that clause complex, having only a non-structural, cohesive link to the clause complex they are enclosed within. However, if there is felt to be a strong pressure to read or speak the enclosed clause or clause complex with tone concord, this suggests a relationship of elaboration, since tone concord is often the only marker of elaboration. Interpreted in this way, the tactic structure of the example would be xβ1 ^ xβ=21 ^ xβ=2+2 ^ α, where the aside is analysed as an elaboration of the hypotactically enhancing temporal clause by the time I come to the end of a particular form.