Halliday & Matthiessen (1999: 19-20):
Suppose we now consider the semogenic processes whereby this potential expands. (i) We may, for example, construe new participants by creating new thing/name complexes: thus
Of course, the 'thing' may have been 'there' all along but it is only newly observed and semanticised:
Here we are extending the system by constructing new semiotic domains.