This image shows the Define Primary Keys page. This page includes the following text:

The [Table Name] table does not have a primary key defined, but the Database Adapter must be able to uniquely identify a given row. Please select the fields below that can be used as a virtual primary key. (Your database table is not altered.)

Below this text is a rectangular box, with the Table Name and the fields displayed.

At the bottom are the standard Help, Back, Next (grayed out), Finish (grayed out), and Cancel buttons.