Halliday & Matthiessen (1999: 76):
… the definition construes a token-value relation between a fairly delicate semantic type that is lexicalised within the lexicogrammar and a restatement of this type by means of other resources in the ideation base. The restatement draws more on the resources towards the grammatical end of the scale, so that in the definition a lexicalised token is construed as a grammaticalised value. This entails a shift from construing experience through depth in the experiential taxonomy towards construing experience through expansion in a logical sequence.