A trial court abuses its discretion if it allows a party to call a witness who has not been disclosed despite a Rule 213(f) interrogatory. Such a witness should be barred even though not testifying as to any "opinion." No. American Service Insurance Co. v. Olszewski, No. 1-01-0515, 2001 WL 968106 (1st Dist. Aug. 20, 2001).