The Division of Enforcement, the Market Participants Division, the Division of Clearing and Risk, the Division of Market Oversight, or the Division of Data may participate in any proceeding by filing a notice of appearance. Such a notice shall be filed and served on or before the twentieth day following the date of service of its brief by the National Futures Association. The Commission shall by order establish a supplementary briefing schedule for the Commission staff and other parties to the proceeding. If it concludes that participation of the Commission staff will not serve the public interest, the Commission shall prohibit further participation.