Key Type controls
When the current time is on a keyframe (the keyframe block will be highlighted yellow), you can use the following buttons to control the type of keyframe at that time.
Spline Curve
When Spline Curve is selected, the envelope will be a smooth curve through the keyframe.
Linear
The envelope will be a straight line to the current keyframe.
Value Jump
When this is selected, the value will remain at the previous keyframe’s value until the exact moment of the current keyframe, then it will jump to the new value. This is great when you want an object to disappear at a specific point in time. You can set up an envelope for the object’s Dissolve value where the first keyframe is 0%, and the second keyframe is a Value Jump keyframe to 100%. This will guarantee that the object will disappear instantaneously rather than fading out over time.