A text field called FirstLast in FileMaker Pro 13 is set to auto-enter the following formula:

FirstName & " " & LastName -
FirstName and LastName are text fields in the same table. The option Do not evaluate if all referenced fields are empty is unchecked. The option Do not replace existing value of field (if any) is checked.
Under which two circumstances will the value of the calculation be inserted into the FirstLast field? (Choose two.)