Martin (1992: 403-4):
IDENTIFICATION is abstracted from nominal group DEIXIS, and alongside the lexicogrammatical systems of SUBSTITUTION and ELLIPSIS is a powerful measure of contextual dependency and thereby strongly associated with MODE.
 The discourse semantic system of identification is presented as the semantics of reference. However, rather than being theorised at a more abstract level than this cohesive system, a reworking of it has merely been moved to a different location within the theory.
 The nominal group system of deixis realises an orientation to the '"speaker-now", the temporal–modal complex that constitutes the point of reference of the speech event' (Halliday & Matthiessen (2004: 314). The system of identification is a reworking of the non-structural cohesive system of reference, not the structural system of deixis.
 This discussion (p33) misconstrued context as co-text and material setting. See original critique here.
 The "association" of these systems with the contextual system of mode is not due to their being 'a powerful measure of contextual dependency'. Substitution–&–ellipsis and reference (the source of identification) are both systems of the textual metafunction, and mode is the contextual stratum system of the textual metafunction.
 In SFL theory, the realisation of the contextual system of mode in textual meaning and wording varies according to register.