These ʻmacro-functionsʼ have been recognized for a long time in ʻfunctionalʼ theories of language (for this reason we retain the name ʻfunctionʼ for them). By using the notion of a grammatical system, we can show more clearly how they are embodied in the grammar, where they appear as relatively discrete areas of formalized meaning potential, or in other words relatively indipendent sets of options. We referred to these as ʻfunctional componentsʼ of the grammar. Three principal components can be recognized under the headings ʻideationalʼ, ʻinterpersonalʼ and ʻtextualʼ.
- Halliday (1973), a pag.99