Halliday & Matthiessen (1999: 59-60):
Participant rôles in figures are filled by elements of the type 'participant'; they are phenomena capable of taking on a participant rôle in a process configuration, e.g. bringing it about or being affected by it. They are further differentiated according to two parameters: see Plate 5. Macro-participants are all metaphorical and will be left out of consideration for the time being. Simple participants may be things or qualities.
