On grammatical class:
- fa'a
- location tense relation/direction; arriving at/directly towards ...
- to'o
- location tense relation/direction; departing from/directly away from ...
- ze'o
- location tense relation/direction; beyond/outward/receding from ...
- zo'a
- location tense relation/direction; tangential to/passing by ...
- zo'i
- location tense relation/direction; nearer than .../inward/approaching from ...