Witness List. Prior to the hearing, and whether or not a prehearing conference is held, the Secretary may order that each party make available to the other parties the names and written reports of experts and other witnesses the party expects to call. Failure to comply in good faith with the order is grounds for the refusal to admit the oral or written testimony of that witness or a report of that expert. Oath or Affirmation. Witnesses shall take an oath or affirmation to tell the truth. Exclusion from Proceedings. On request of a party, the Secretary shall exclude witnesses other than parties from the hearing room, except when testifying. A party, representative, witness, spectator, or other person may not disclose to any witness excluded under this section the nature, substance, or purpose of any testimony, exhibit, or other evidence introduced during that witness' absence. A party that is not an individual may designate an employee or officer to remain in the hearing room as its representative, even though the employee or officer may be a witness. An expert witness who is to render an opinion based on testimony given at the hearing may remain during that testimony. If a witness receives information in violation of this section, the Secretary may: Exclude the testimony of that witness; or Take other appropriate action.