In integrated CAD different techniques are used to model various features (informations, activities, data and data flow) of the problem domain. Because they model the same real world topic, all aspects developed using different techniques must be compatible and able to cooperate. Since most modelling techniques were developed independently, co-operation is not encouraged. We propose an object oriented modelling approach borrowed from object oriented software design that offers methods and notations for both static and dynamic aspects of state and behaviour of the models and yields smoother development into implementations with object-oriented languages and databases. The paper discusses the motives, the details of the OO modelling approaches and an example from the domain of standards representation. It has been found out that particularly the introduction of the mechanism concept enables and forces us to think about new features of our models.