Transform controllers are compound controllers. They set the type and behavior of the controllers used for Position, Rotation, and Scale.
You assign Transform controllers using either Track View or the Motion panel, but compound Transform controllers do not display properties in Track View. You can access the parameters of Transform controllers only in the Motion panel.
The Position/Rotation/Scale (PRS) controller is the default Transform controller for most objects. The PRS Transform controller sets up default Bezier Position, TCB Rotation, and Bezier Scale controllers.
Use a PRS controller whenever you want a standard transform set up or when you want complete control over the Position, Rotation, and Scale controllers.
The Transform Script controller contains all of the information contained in a PRS Controller in one scripted matrix value. Instead of having three separate tracks for position, rotation, and scale, all three values can be simultaneously accessed from one script controller dialog. Because the transform values are defined by a script, they are easier to animate.
The value of the controller script must be a matrix3 value. A matrix3 value is a 4x3 3D transformation matrix. For more information, see the Matrix3 Values topic in the MAXScript Reference.