Topic: version 4 MAXScript New Features/Constraints
Path_Constraint - superclass: PositionController
A path constraint restricts an objects movement along a spline or at an averaged distance between multiple splines.
Path Target Object
A path target can be any type of Spline. The spline curve (target) defines a path of motion for the constrained object. Targets can be animated using any of the standard translation, rotation, scale tools. Setting keys on the path's sub object level, such as vertex, or segment will animate the path while effecting the constrained object.
See also
Orientation Constraint Controller