Character Animations - Learning Game AI Programming with Lua - page 165

Animation weights
Animation blending is done through the manipulation of how much each animation con-
tributes to the skeleton. As animation weights must be between 0 and 1, the animation sys-
tem knows how much to contribute to the skeleton based on the weight's percentage to 1.
Any values below 0 or above 1 are clamped by the sandbox:
local weight = Animation.GetWeight(animation);
Animation.SetWeight(animation, weight);