Martin (1992: 142):
Where chains are initiated exophorically or homophorically this raises the question of how to analyse subsequent mentions of the same participant. The most economical strategy is to code the first member of the chain as exophoric or homophoric and subsequent realisations as anaphoric. It then follows from the way the chain initiating item is coded that the rest of the realisations in the chain are interpretable as both anaphoric and exophoric or homophoric as well. This strategy is illustrated for [3:80] and [3:81] below.
Pass me that one, will you?
— Here, take it.
You've been drooling over it for more than an hour.
Is the cat in?
— Yes, she's upstairs;
get her dinner out, will you?
 This confuses ideational denotation (construing a participant) with textual reference (referring to a participant).
 This confuses ideational denotation (realising a participant) with textual reference (referring to a participant).
 This demonstrates the absurdity that results from mistaking nominal groups for reference items. Here Martin's model identifies the participant her dinner with the participant the cat. In SFL theory, it is the reference item her that refers anaphorically to the cat.