Halliday & Matthiessen (1999: 192):
typifying rôles: acting participant in a figure of saying [Sayer, e.g. the ministry announced …], of doing [Actor, e.g. the school is closing down]; also of sensing [Senser, e.g. the class decided that…].
pronoun it/they; general noun people, place, set-up etc.; number category: count (singular). (Institutions of course do appear in the plural — although relatively infrequently: the plural pronoun they typically refers to a single institution.)
has potential for voluntary action, typically semiotic with authority of a collective [verbal process of ordering, mental process of deciding or judging]; also material [material processes, middle and effective].