Aspect
Aspect is how an action unfolds (is it ongoing, completed, or done-and-still-relevant?) as opposed to tense, which is when it happens.
OVP marks aspect with verb suffixes: -ti (ongoing: "is/was eating"), -ku (completed: "ate"), and -pü (present perfect: "has eaten," and it still matters). Notice -ti doesn't say when: tüka-ti is "is eating" or "was eating," with context filling in the time.