Sets the ID of the form you want to use as a lookup.
For text boxes, this value is set to the LookupFormID property value set for the table.
For tables, the default value LookUpFormID property is <Undefined>. By changing this value, you can determine which form is displayed when users press F6 (Lookup). For example, the LookupFormID property on the Customer table (18) is set to the Customer List form.