This paper presents an application data model for the representation of conceptual structures of mechanisms. The main features in building this model are (1) to use semantic database modelling approaches and (2) to have a generic model. The model has been used in developing a software environment system for integrated design and manufacturing of mechanisms. Both conceptual design and implementation issues concerning this model are discussed. The system intelligence can be increased via a proper application data model. In particular, the concepts handling raw data and handling different views from the same object are clarified. The necessity and the technique to support them are discussed both in a general sense and in our mechanism data model.