Instances of rotational-joint class and manipulator class constitute a Manipulator Model. rotational-joint is a subclass of the body. manipulator is a subclass of the cascaded-coords. rotational-joint class defines models of manipulator joints. manipulator class has methods for solving a forward kinematic solution and inverse kinematic solution.
The way of the definition of a manipulator is that i) Make all the joints of the manipulator, ii) Integrate these joints into manipulator.