     }
     
     /// A reference to the animation duration.
-    fileprivate var animationDuration: TimeInterval = 0
+    fileprivate var transitionDuration: TimeInterval = 0
     
     /**
      A reference to the animation total duration,
      which is the total running animation time.
      */
-    fileprivate var animationTotalDuration: TimeInterval = 0
+    fileprivate var transitionTotalDuration: TimeInterval = 0
     
     /// A reference to the animation start time.
-    fileprivate var animationStartTime: TimeInterval? {
+    fileprivate var transitionStartTime: TimeInterval? {
         didSet {
-            guard nil != animationStartTime else {
+            guard nil != transitionStartTime else {
                 displayLink = nil
                 return
             }

    }
    
    /// A reference to the animation elapsed time.
    open fileprivate(set) var animationElapsedTime: TimeInterval = 0 {
        didSet {
            guard isTransitioning else {
                return

    
    /// Cleans the transition values.
    fileprivate func cleanTransitionValues() {
        transitionStartTime = nil
        transitionElapsedTime = 0
        transitionTotalDuration = 0
    }
}
