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DOMAIN MODELING OF OBJECT-ORIENTED INFORMATION SYSTEMS 147
Figure 9.2 Conceptual Schema Diagram for the Order

F1
Name

Customer
(ID)
F2
Phone
on
(nr)
F6
for

F3
Order Date
(number) ordered-on (dd/mm/yyyy)

Product . In Order . Has Qty . F7 Quantity

(nr+)

F4
Name

Product
(code)
F5
UnitPrice
($)

the new information. It is useful to note that with ORM, (1) not only is the stability of the model
preserved but also (actually the other side of the same coin) (2) the changes to the model reflect
precisely the changes in our cognition of the domain.

THE GYMNASTIC CASE STUDY

This case study was originally published in White (1994). The problem statement below is a
paraphrase of the original version, with some minor modifications that will be pointed out.
The purpose of the Gymnastics System is to keep information on the gymnasts, their clubs,
and the competitions among the clubs during one season.