The foreign key attribute may have the same name as the primary key attribute from which it was derived, or a role name can be used as the name of the foreign key attribute.

The following figure illustrates the use of roles.

In this example, the primary key of the entities BORROWER and FORM LETTER are both named ID. Clearly the ID of a BORROWER is not the same thing as the ID of a FORM LETTER. The role name “Borrower ID” is given to the primary key of BORROWER and the role name “Form Letter ID” is given to the primary key of FORM LETTER.