Enforcement action means any action taken by the Chair under 25 U.S.C. 2713 against any person engaged in gaming, for a violation of any provision of IGRA, the regulations of this chapter, or tribal regulations, ordinances, or resolutions approved under 25 U.S.C. 2710 or 2712 of IGRA, including, but not limited to, the following: A notice of violation; a civil fine assessment; or an order for temporary closure. Enforcement action does not include any action taken by NIGC staff, including but not limited to, the issuance of a letter of concern under § 573.2 of this chapter.