We are doing grammar, not notional semantics (well, I think so at least), so we need to use grammatical tests to determine process types. Not a reference to "same meaning".
and then again on 28 June 2013:
We need to follow the grammatical PRINCIPLES that Halliday established (how to argue Linguistically) rather then the grammatical FACTS that he put forward on the basis of applying these principles.
Halliday's 'principle' for grammatical analysis is to take a trinocular perspective, which means also looking at the grammar 'from above' (what meaning is being realised) and 'from below' (how the wording is realised) — not just 'from roundabout' (the level of grammar). As Halliday & Matthiessen (2004: 31) make clear:
We cannot expect to understand the grammar just by looking at it from its own level; we also look into it ‘from above’ and ‘from below’, taking a trinocular perspective. But since the view from these different angles is often conflicting, the description will inevitably be a form of compromise.
O'Donnell's application of the term 'facts' to theory, rather than data, betrays an epistemological confusion. 'Facts' are the construals of experience from which theory is designed.