A Reference is a form of an Attribute and is added to a form in the same way as any other Attribute. They allow for storage of multiple values and to process information in a tabular form, accessing individual items in the array by using a Reference to present the cell in an Array.
To add a Reference to a form, perform the following:
Set the PresentationType property of the owner of the Reference element to a value other than None.
Enter a logical condition in the Constraint field that must remain true for the Reference element.
Set the Direction property of the Reference to a value other than None, or drag the Reference from the Class View onto the form of the owner. Follow the instructions for Dragging an Attribute from the Class View on how to add a Reference element.