Halliday & Matthiessen (2014: 397):
A striking feature of this structure is its parallelism with the nominal group. The verbal group begins with the Finite, which is the verbal equivalent of the Deictic, relating the process to the ‘speaker-now’; the Finite does so by tense or modality, whereas the Deictic does so by person or proximity, but each of these provides the orientation of the group. The verbal group ends with the Event, which is the verbal equivalent of the Thing; the former expresses a process, which may be an event, act of consciousness or relation, whereas the latter expresses an entity of some kind, but both represent the core of the lexical meaning.