Halliday & Matthiessen (2014: 666, 667):
The semantic system of EXPANSION may be contrasted in this respect with that of FIGURATION: see Figure 10-2. The grammatical realisation of FIGURATION is ‘compact’, being confined to the TRANSITIVITY system of the clause. In contrast, the grammatical realisation of EXPANSION is ‘dispersed’, ranging over more than one grammatical unit. (We shall see later that compactly realised systems such as configuration may become dispersed in their realisation through the process of grammatical metaphor.)
