Sub-range start for partial easing (0–1).
Sub-range end for partial easing (0–1).
RPE easing type (1–28).
Speed at endTime.
Event end beat as a Beat tuple.
End beat as a plain number.
Link group ID (0 = none).
Speed at startTime.
Event start beat as a Beat tuple.
Start beat as a plain number.
A speed event (note scroll speed over a beat range).
Speed events do not support bezier easing and stepped interpolation is used by most engine versions.