Abstract: A computer aided design (CAD) system is described where each type of change in a CAD-generated object is automatically and chronologically protocoled so that the object directly includes an abstract description of the history of the object independent of the CAD module used. This is particularly advantageous with decentralized CAD systems in which several constructors/designers are working together on the same draft, but located in different places. At the end of a session, the object history, i.e., the changes which have taken place, are directly exported, together with the object data, into the destination system. The abstract description is in a form independent of the system used.