Martin (1992: 508):
Mode refers to the rôle language is playing in realising social action. Within register, it is the projection of textual meaning, and so is realised primarily through the textual metafunction in language. Mode thus puts major systems such as TONALITY and TONICITY in phonology, and THEME and INFORMATION (clause), DEIXIS (nominal group), TENSE (verbal group) and SUBSTITUTION and ELLIPSIS (clause and group) in the grammar at risk, and because of their textual orientation impacts on all systems at the level of discourse semantics (NEGOTIATION, IDENTIFICATION, CONJUNCTION and IDEATION).
 To be clear, Martin's 'register' is a misconstrual of culture (context) as a functional variety of language (register). In SFL theory, mode is the "projection" of the textual metafunctional principle onto context, in modelling culture as a semiotic system, not the projection of textual meaning.
 Information is not a system of the clause. It is a system of the information unit (Halliday & Matthiessen 2014: 115).
 Deixis is not a textual system of the nominal group. It is an interpersonal system (Halliday & Matthiessen 2014: 387). Deixis functions textually in the cohesive system of reference.
 Tense is not a textual system of the verbal group. Tense is realised by the logical structure of the verbal group (Halliday & Matthiessen 2014: 398).
 Strictly speaking, substitution-&-ellipsis is not a system of the clause and group. Rank systems are structural. As a system of cohesion, it is non-structural. The clause and the group are domains in which it operates.
The other cohesive systems — reference, conjunction and lexical cohesion — are also relevant here, but omitted because Martin has misconstrued them as discourse semantic systems of various metafunctions: identification (textual), conjunction (logical) and ideation (experiential), respectively.
 This exemplifies Martin's confusion between text as a semantic unit, and the textual metafunction as a dimension of semiosis. See  above.