Martin (1992: 129):
Notes ii, iii, iv, v, vi and viii index the text as that of a young writer. The problems referred to in ii and viii are almost certainly graphological in origin; but the others point to immature use of the IDENTIFICATION system, given the genre (recount of personal experience…) and mode (written — see Chapter 7 below).
 To be clear, the problem cited in ii is the lack of deixis in I saw Rhinocerous. As the capitalisation suggests, the writer was unsure as to whether this was a proper name. On this basis, the problem is thus not "graphological in origin". On the other hand, the problem cited in viii is the misspelling of 'it' as I. As the word 'it' is correctly spelt elsewhere, this was clearly a momentary error, rather than an instance of deficient graphological potential.
 To be clear, of these four "problems", the only instance that could be regarded as "immature" use of textual reference is the problem cited in vi , wherein the anaphoric reference of it is to feeding instead of 'food'.
Of the remaining three "problems", two are shortcomings in Martin's analysis. The "problem" cited in iii, and I saw the tiger, is Martin's failure to recognise the anaphoric reference of the to the title at the zoo, and the "problem" cited in iv, and this man was feeding him is the same failure to recognise the anaphoric reference of this to the title at the zoo.
On the other hand, the "problem" cited in v is the switch from he to it in referring to the tiger. This switch may just reflect the realisation of the female writer that her previous assumption that the tiger is male may be mistaken. On this basis, the second reference can be seen as self-correction.
In other words, the "problems" cited by Martin cannot be seen as either graphological in origin, or (in all but one case) as 'immature' use of reference (misconstrued as IDENTIFICATION); moreover, two of the "problems" arise only because of Martin's inability to recognise reference relations.
It might also be observed that the focus here on writing pedagogy distracts attention away from the question of the theoretical utility of Martin's IDENTIFICATION system.