On grammatical class:
- ca'a
- modal aspect: actuality/ongoing event.
- ka'e
- modal aspect: innate capability; possibly unrealized.
- nu'o
- modal aspect: can but has not; unrealized potential.
- pu'i
- modal aspect: can and has; demonstrated potential.
- na'epu'i
- modal aspect: has never, and perhaps cannot; other-than-demonstrated-ability.