Halliday & Matthiessen (2014: 623):
The textual status at issue in the system of reference is that of identifiability: does the speaker judge that a given element can be recovered or identified by the listener at the relevant point in the discourse or not? If it is presented as identifiable, then the listener will have to recover the identity from somewhere else (for a systemic description of this as a semantic system, see Martin, 1992). If it is presented as non-identifiable, then the listener will have to establish it as a new element of meaning in the interpretation of the text.
Blogger Comments:
To be clear, Martin (1992) misunderstands the notion of cohesive reference, confusing it with nominal group deixis and reference in the sense of ideational denotation. Moreover, it is not a semantic description, but merely a relabelling of (misunderstandings of) Halliday & Hasan's (1976) grammatical system. Evidence: