Lets you assign and append different transform controllers to individual objects. you can assign those controllers that apply to move, rotate, and scale operations in the Motion Panel/Assign Controller rollout.
Animation Controllers are plug-ins that handle all of the animation tasks in 3D Studio Max. For a complete list of available Animation Controllers, see the Assign Controller (Track View) help topic.
Assign Controller: Display the Assign Controller dialog. If no track is selected, the Assign Controller button is grayed out.
Select a controller from a list of available controllers in this dialog.
Depending on the type of track you have selected, the Choose Controller dialog displays a subset of the different types of controllers. Rotation controllers, for example are only available for rotation tracks.
The default TCB Rotation Controller is replaced with the Euler XYZ controller.