Whether the specified Rigidbody2D.SlideMovement.startPosition should be used or not.
When false, the Rigidbody2D.SlideMovement.startPosition will not be used but instead the current Rigidbody2D.position will be used.
When true, the specified Rigidbody2D.SlideMovement.startPosition will be used.
Additional resources: Rigidbody2D.SlideMovement.startPosition, Rigidbody2D.Slide and SlideResults.