I believe it's the relation between multiple tweens. If you are using multiple tweens with different durations for TweenMax, for example duration 1
and duration 2
, then second tween will happen over twice the number of pixels in relation the the first tween.
Since it's just a relation between tweens, the number doesn't matter. It can be 1
and 2
or 1000
and 2000
. The outcome would be the same.