Add, move or delete single points on one axis at exact times. Every other point stays as it is. add puts each point exactly where given and replaces an existing point within replace_within_ms of it. remove_at_ms deletes the point nearest each time, within replace_within_ms. To move a point, remove its old time and add the new one. Points are not speed fitted; the result lists any part now too fast for devices. Lands in the editor at once as one Undo step.