This article first appeared in the August 1998 issue of the Journal of Conceptual Modeling.
Fourth in a series of articles examining data modeling in UML from the perspective of ORM, this paper examines associations in more detail, contrasting ORM nesting with UML association classes, and ORM co-referencing with UML qualified associations, then discusses exclusion constraints, and summarizes how the two methods compare with respect to terms and notations for data structures and instances.