ABSTRACT
This chapter is responsible for discussing some of the main pillars of the architecture of systemic functional linguistics (SFL). In 1961, when he first put forward a coherent and comprehensive architecture for the theory of grammar, Halliday included layers (levels), categories (system, structure, unit and class) and scales (rank, delicacy and exponence). These are all still relevant to SFL today, although levels are now called ‘strata’, under the influence of Lamb’s stratificational linguistics (for example Lamb 1964) and they have been joined by a second kind of layering, that of the metafunctions. Exponence has been further distinguished as realisation and instantiation.
