Halliday & Matthiessen (1999: 144):
Figures of being & having construe relations between participants. They construe the same overall range of relations as expanding sequences, and the basic subtypes also correspond to the subcategories of expansion, viz elaboration, extension, and enhancement. Once we realise that the semantic system construes phenomena according to trans-phenomenal (fractal) principles, it will seem natural that figures of being & having construe relations in such a way that they resonate with the semantic types manifested in expanding sequences. They do not construe an arbitrarily different theory of relations. In a figure of being & having, one participant may thus elaborate, extend, or enhance another one.