Role Qualifier
A qualifier is an attribute whose values partition the set of objects related to an object across an association.
Example: An order includes several order lines. The order line number can be used as the qualifier that identifies each line.
To specify a qualifier:
1. Right-click the role and select Properties.
The Properties dialog box of the role opens.
2. Select the Qualifiers tab.
3. To add a new qualifier to a role, right-click in the dialog box.
4. In the pop-up menu that appears, select New. The same pop-up menu can then be used to modify the qualifier properties.
Several qualifiers may be needed to uniquely identify each object in a class.
For example, each square on a chessboard is identified by its row number and column number on the chessboard.
