Cutscene Tracks are added within Cutscene Groups. Certain Tracks can only be added to certain Groups, like for example the CameraTrack is able to only be added to the Director Group, or the Mecanim Track can only be added to the Actor Group, while other can be added to both. The following Cutscene Track types exist in general:
Tracks are always sampled from bottom-to-top, thus in specific tracks where ordering matters, it’s good to remember that tracks on the top, always have the last word. So for example if you have two Subtitles clips one above the other, only the top-most will take place at the same time, or if you have two or more animated property clips targeting the same property, only the top-most will take effect at the same time as well. Tracks can be re-ordered within their own group and they can also be disabled/muted if so required through their right click context menu.