Identifying Attributes Dialog Box (Model Designer)
Select the attributes that identify the instance of the selected entity as unique. For example, suppose your report model contains an entity that lists every store by name and by territory number. You can have numerous duplicate store names but every store must have a unique territory. The field that contains the territory would be an identifying attribute. When Report Builder users drag the entity to the design area, the identifying attributes are displayed by default.
Lists the attributes that you have added in the order that they should be displayed. You can change the order of the attributes by clicking the Up or Down arrow buttons to the right of the list box.
Click the Add button to launch the Add Attributes dialog box and select the attributes that you want to add to this entity.
Click the Remove button to remove the selected attribute from the Members list.
The Properties list box displays the attribute name and path of each member of the list box.