Martin (1992: 121-2):
As noted above, proper names regularly depend on information retrieved from the context of culture. The definite article is commonly phoric in this way as well, presuming information available through membership in communities of any size. Some typical examples are presented below, scaled with respect to the size of the community involved.
examples of reference to the context of culture (homophora)
[community] [homophoric nominal group] English speakers the sun, the moon nations the president, the governor states the premier, the Department of Education businesses the managing director, the shareholders offices the secretary, the photocopier families the car, the baby, the cat
Technically, reference of this kind is referred to as homophora. It is used when interlocutors' membership in a particular community means that certain participants can be treated as inherently "given".
 There are several confusions here. Firstly, proper names are not reference items, since they do not present an item as identifiable; instead, they present an identity. Here Martin again misconstrues textual reference as ideational denotation. Secondly, the meaning denoted by a proper name is semantic, not contextual. Thirdly, context of culture and text are at opposite poles of the cline of instantiation, the former being potential that is realised by language as potential, the latter being an instance of language that realises an instance of context: a context of situation.
 This misunderstands homophoric reference. As the term makes plain, 'homophoric' means self-pointing; that is 'self-specifying; there is only one – or at least only one that makes sense in the context' (Halliday & Matthiessen 2014: 631).
 To be clear, the size of the community is irrelevant to any of the points being made.
 This confuses human collectives (actual language users) with context of culture (cultural potential realised by language potential).
 This confuses the reference item (the) with the grammatical domain in which it is located.
 This is misleading. The referential function of the non-specific demonstrative (the) depends on how it it used in a text. The reference of all of these examples may exophoric, including homophoric, but it may also be endophoric: anaphoric or cataphoric. To be clear, only endophoric reference is cohesive.