Labels:text | screenshot | font | number OCR: FORM RELATIONSHIP BETWEEN Form 1: Invoice If Form 1 is Subform, how should Key field be updated when Main form Key is modified: Null [Blank) : . :: /". & Form 2: Product If Form 2 is Subform, how should Key field be updated when Nain form Key is modified: Restrict (Don't Update) BASED ON THE FOLLOWING FIELDS BEING EQUAL: (Define at least one set] Field Product Code Product Code And Field And Field OPTIONAL RELATIONSHIP NANES: [Form names are used as a default. ] for Form 1; Form 2: Lookup Product Code Figure 4. DataEase maintains referential integrity when defining the relationship between product and invoice.