Martin (1992: 117):
The feature [semblance] could be further subclassified, into [identity] and [similarity]. This makes it possible to note the ways in which the features [presenting] and [presuming] condition its realisation; such occurs only in the context of presenting reference, same only in the context of presuming reference.
PRESENTING PRESUMING SIMILARITY a similar frog;such a frog the similar frog; IDENTITY an identical frog;an equal amount the identical frog;the equal amount;the same frog/amount
 Here again Martin presents a distinction in Halliday & Hasan (1976: 76) as his own work, rebranding his misunderstanding of their grammatical distinction as his discourse semantic distinction.
the practice of taking someone else's work or ideas and passing them off as one's own.
synonyms: copying, infringement of copyright, piracy, theft, stealing, poaching, appropriation;
See also Jim Martin "Honouring" The Late Ruqaiya Hasan where Martin falsely accused the late Ruqaiya Hasan of plagiarism at a symposium organised to honour her.
 To be clear, Martin's distinction between presenting and presuming reference is his rebranding of Halliday & Hasan's grammatical distinction between non-specific and specific deixis, misunderstood as reference and relocated to his discourse semantic stratum; see previous posts.
 As these constructed examples demonstrate, reference is here misunderstood as feature of nominal group structure. No attempt is made to provide, in a constructed co-text, a frame of reference by which something is 'the same or different, like or unlike, equal or unequal, more or less' (Halliday & Matthiessen 2014: 632).