Halliday & Matthiessen (2014: 601):
It is helpful to have a term for this general phenomenon – i.e. the creation of meaning in the course of the unfolding of text. We shall call it logogenesis, with ‘logos’ in its original sense of ‘discourse’. Since logogenesis is the creation of meaning in the course of the unfolding of a text, it is concerned with patterns that appear gradually in the course of this unfolding; and the gradual appearance of patterns is, of course, not limited to single texts but is rather a property of texts in general instantiating the system of language. Such patterns have been called emergent patterns and when we focus on grammar we are concerned with patterns of emergent grammar (as formulated by Hopper, e.g. 1987, 1998). We shall refer to the version of the system created in the course of the unfolding of a text as an instantial system since it represents a distillation of patterns at the instance pole of the cline of instantiation.