Halliday & Matthiessen (1999: 89, 90):
The ideation base construes phenomena as organic wholes that may take on roles in other kinds of phenomena; but it also deconstrues many such organic wholes into their component parts. When these component parts are phenomena of the same type — participants (e.g., chair: legs, seat, back), figures (e.g., baking a cake: stages in the procedure), this is known as meronymy (or meronymic taxonomy; cf. meros 'part'). We find local taxonomies of this kind, often interlocked with hyponymies; for example, see Figure 2-16. Taxonomies thus embody the two types of expanding relationships we mentioned at the beginning of this section — extension and elaboration. The meronymic type of taxonomy is extension, whereas the hyponymic type is elaboration.
