Systemic functional grammar (SFG) is a form of grammatical description originated by Michael Halliday. It is part of a social semiotic approach to language called systemic functional linguistics. In these two terms, systemic refers to the view of language as "a network of systems, or interrelated sets of options for making meaning"; functional refers to Halliday's view that language is as it is because of what it has evolved to do (see Metafunction). Thus, what he refers to as the multidimensional architecture of language "reflects the multidimensional nature of human experience and interpersonal relations." Influences Halliday describes his grammar as built on the work of Saussure, Louis Hjelmslev, Malinowski, J.R. Firth, and the Prague school linguists. In addition, he drew on the work of the American anthropological linguists Boas, Sapir and Whorf. His "main inspiration" was Firth, to whom he owes, among other things, the notion of language as system. Among American linguists, Whorf had "the most profound effect on my own thinking". Whorf "showed how it is that human beings do not all mean alike, and how their unconscious ways of meaning are among the most significant manifestations of their culture". From his studies in China, he lists Luo Changpei and Wang Li as two scholars from whom he gained "new and exciting insights into language". He credits Luo for giving him a diachronic perspective and insights into a non-Indo-European language family. From Wang Li he learnt "many things, including research methods in dialectology, the semantic basis of grammar, and the history of linguistics in China". Basic tenets Some interrelated key terms underpin Halliday's approach to grammar, which forms part of his account of how language works. These concepts are: system, (meta)function, and rank. Another key term is lexicogrammar. In this view, grammar and lexis are two ends of the same continuum. Analysis of the grammar is taken from a trinocular perspective, meaning from three different levels. So to look at lexicogrammar, it can be analysed from two more levels, 'above' (semantic) and 'below' (phonology). This grammar gives emphasis to the view from above. For Halliday, grammar is described as systems not as rules, on the basis that every grammatical structure involves a choice from a describable set of options. Language is thus a meaning potential. Grammarians in SF tradition use system networks to map the available options in a language. In relation to English, for instance, Halliday has