Length in frames: the tween has positions 0 to duration
Start positions of the tween's steps, in order. createjs derives the frame of a SYNCHED / SINGLE_FRAME child placed by this tween from the distance between the current position and the start of the step containing it (the last step whose start is at or before the position).
The properties this tween writes, i.e. its managed properties
What the tween writes to
Index into the runtime content's writer list: the function that writes a frame's values (values[frames[position]]) to the target, one property after another by name (null when the tween writes no property)
A tween as written in runtime content (tweenOf makes its values for every position)