Halliday & Matthiessen (1999: 376, 377):
The semantic system, or "meaning base", thus consists of the three familiar metafunctional contributions: the ideation base, the part of the meaning base that we have focussed on, but also the other two bases, the interaction base and the text base. All three bases are extended along the cline of instantiation from potential to instance. … Table 9(1) summarises those aspects of the three bases to be discussed.
