This chapter has presented the fuzzy extensions to ER/EER and UML data models to cope with fuzzy as well as complex objects in the real world at a conceptual level. Some major notions in these data model have been extended and the corresponding graphical representations were developed. It is not difficult to see that a classical conceptual data model is essentially a subset of the corresponding fuzzy conceptual data model. When there is not any fuzziness in the universe of discourse, the latter can be reduced to the former.
The fuzzy ER/EER and UML data models can be applied for conceptual modeling of imprecise and uncertain engineering information in addition to the conceptual design of the fuzzy databases. But limited by their power in engineering information modeling, some data models for engineering should be extended fuzzily for imprecise and uncertain engineering information modeling.