Halliday & Matthiessen (1999: 468):
In the temporal instantiation perspective, the issue is the occurrence of the process as an event located in time: how does it unfold through time, and what is its temporal profile? Here the relevant variables are such as the following:
1. Is the process homogeneous during its occurrence or does it decompose into a sequence of distinct phases (stages); is it a mini-tableau or a mini-drama?These questions lead to typologies that include terms like stative, dynamic, perfective, imperfective, punctiliar, iterative, and so on.
2. Is the period of occurrence a relatively short interval, or is it an extended interval?
3. Is the whole period of occurrence in view or only a phase of it (e.g. beginning or end)?
4. Does the process tend to occur once or repeatedly?