Modification of a model in situations, where one end of several parts should be transferred for the same distance, for instance, has posed a problem in modeling systems. The problem can be solved by defining a magnetic control plane to which model part handles locating thereon will adhere without separate definitions given by the user and they move (406) along with the plane. The only thing the user needs to do is to create a plane and to define the plane type to be a magnetic control plane. On the basis of these data given by the user the modeling system knows what to transfer when the magnetic control plane is transferred.