Martin (1992: 318):
Matthiessen (1922) sums up the semantic continuity between participants and circumstances as outlined in Fig. 5.22, which also brings out their nuclearity with respect to the Process:
Figure 5.22. Nuclearity: participants and circumstances (following Matthiessen 1992)
The elaboration, extension and enhancement analysis presented above provides an alternative perspective on peripherality. Matthiessen's diagram can be amended in line with this perspective by treating Process°Range:process structures as more nuclear than Process°Medium ones. Range:entities could be left as more peripheral than Mediums since like Agent and Beneficiaries they have both prepositional and non-prepositional realisations… .
 In the context of this discussion, the label 'Process + Medium' in Martin's representation of Matthiessen's diagram implies an extension relation between the two functions. In SFL theory, the relation between Process and Medium is construed as one of complementarity within the Nucleus (Halliday & Matthiessen 1999: 154).
 This "alternative perspective" has been shown in previous posts to be one that only arises through multi-dimensional misunderstandings of SFL theory.
 amend verb 'make minor changes to (a text, piece of legislation, etc.) in order to make it fairer or more accurate, or to reflect changing circumstances'. "Amending" Matthiessen's diagram would not make it more accurate, but it would 'reflect changing circumstances', namely: not understanding SFL theory.
 In SFL theory, the complementarity of Process and Medium forms the Nucleus to which other functions are related by expansion or projection — the latter being omitted from this alternative perspective. To construe Process°Range: process as 'more nuclear' than the Nucleus betrays a misunderstanding of nuclearity, as demonstrated in previous posts.
 A further inconsistency introduced here is the notion that structures are located on the cline of nuclearity. The cline orders participants and circumstances in terms of nuclearity.
 As explained in a previous post, the ±prepositional realisations are motivated by the textual metafunction and do not bear on the experiential dimension of nuclearity. Moreover, the perspective taken is that of formal not functional theory, namely categorising according to form rather than function.