Halliday & Matthiessen (1999: 315):
One major source of this kind of elasticity [construing phenomena as sequence or figure] is the manifestation of the very general semantic types of projection and expansion throughout the ideation base. In English, as we have shown, we find them manifested both logically as relations and experientially as elements within figures:
[i] logical manifestation:
as relations between figures in the construal of sequences (realised by clause complexes);as relations between processes in the construal of figures (realised by verbal group complexes);
[ii] experiential manifestation:as circumstances within figures (realised by prepositional phrases or adverbial groups);
as circumstantial processes within figures of being & having (realised by relational clauses);
as non-nuclear participants within figures, i.e., participants other than Medium — Agent, Beneficiary, Range (realised by nominal groups with or without a preposition).