Three Planes Of Reality: Experiential, Interpersonal & Textual Time

Halliday & Matthiessen (2004: 280):

Experiential time is time as a feature of a process: its location, its duration or its repetition rate in some real or imaginary history. Interpersonal time is time enacted between speaker and listener: temporality relative to the speaker–now, or usuality as a band of arguable space between positive and negative poles. Textual time is time relative to the current state of the discourse: ‘then’ in the text’s construction of external reality, or in the internal ordering of the text itself.

Circumstance Vs Qualifier [Diagnostic: Thematicity]

Halliday & Matthiessen (2004: 221):

To differentiate them in analysis, we can apply textual probes: in principle, being an element of the clause, a circumstance is subject to all the different textual statuses brought about by theme, theme predication and theme identification. … In contrast, a Qualifier cannot on its own be given textual status in the clause since it is a constituent of a nominal group, not of the clause; so it can only be thematic together with the rest of the nominal group it is part of.

Prepositions Attached To Verbs [Diagnostic: Thematic Agnates]

Halliday & Matthiessen (2004: 278):

There is no simple diagnostic criterion for deciding every instance; but a useful pointer is provided by the thematic structure, which gives an indication of how the clause is organised as a representation of the process …