Halliday & Matthiessen (2014: 332):
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.