An extension called Attribute-Relationship (AR) is proposed to extend the view of having relationship at the attribute level. The attributes that involve in the relationship are termed strong attribute and weak attribute. In the AR extension, the dual roles of the strong and weak attributes and the embedded existence dependence between them are represented through an identifying relationship. Finally, a range of integrity constraints related to this extension are presented.

Toward this goal, we propose the concept of quality data object in which each datum object is associated with appropriate data and procedures used to indicate the quality of the datum object. Specifically, the is-a-quality-of link is proposed to associate a datum object with its corresponding quality description object. The composite object constructed from a datum object and its associated quality description object provides methods which can access object instances which matches consumers' quality requirements. It also provides a set of quality measure methods that compute quality dimension values including currency, volatility, timeliness, accuracy, consistency, and completeness.

We envision that the quality data objects proposed in this paper can be used as basic building blocks for the design, manufacture, and delivery of quality data products. This will enable consumers to measure the quality of data products according to their chosen criteria; and to procure data products based on their quality requirements, hopefully enhancing overall data quality and data reusability. We are currently working to provide a more concrete definition for a data product and to crystallize its characteristics in further detail.