Halliday & Matthiessen (2014: 560-1):
This is the traditional category of ‘apposition’. As with clauses, appositional group or phrase complexes are characterised by tone concord, signalling the semantic relationship of elaboration. The elaborating group/phrase may restate or particularise; restatements include naming, explanatory glossing and shifts in perspective: a number of the themes of elaborating clause complexes are replayed on a smaller scale. Examples:[verbal group:]
(Unfortunately she) got killed, got run over, (by one of those heavy lorries).
Yes, yes you can; || but then I think || emotion has to be – should be, anyhow – shaped by thought.
[nominal group:]
“Too often, human rights in the US are a tale of two nations – rich and poor, white and black, male and female.”
... it’s because we, the elites, are so great [[ that we carried through the changes]] .
Freedom and steam – a political ideal and a source of energy – these were the forces [[ that drove the new age on]].
How does it differ from other ideologies [[that are often associated with socialism]], such as Leninism?
Have you read any poetry in the eighteenth century recently – any Pope?
[adverbial group/prepositional phrase:]
(I couldn’t have done it) alone, without help.
This has just been when? – over the last few days?
Aesthetically, in terms of the vision in your head, what is the relationship between the fiction and the nonfiction?