trade or business of which is a qualified opportunity zone business. . (2) Effective date The amendments made by this subsection shall take effect as if included in section 13823 of Public Law 115–97 . (b) Clarification of substantially all (1) In general Section 1400Z–2(d) of the Internal Revenue Code of 1986 is amended— (A) by striking during substantially all each place it appears in paragraphs (2)(B)(i)(III), (2)(C)(iii), and (2)(D)(i)(III) and inserting for not less than 90 percent , (B) by striking substantially all of the use in paragraph (2)(D)(i)(III) and inserting not less than 90 percent of the use , and (C) by striking in which substantially all in paragraph (3)(A)(i) and inserting in which not less than 90 percent . (2) Effective date The amendments made by this subsection shall take effect as if included in section 13823 of Public Law 115–97 . (c) Certain property excluded from qualified opportunity zone business property (1) In general Section 1400Z–2(d)(2)(D) of the Internal Revenue Code of 1986 is amended— (A) in clause (i), by inserting (other than self-storage property, parking property, stadium property, or disqualified residential rental property) after tangible property , and (B) by adding at the end the following new clauses: (iv) Self-storage property The term self-storage property means property designed and used for the purpose of renting or leasing individual storage space to occupants who are to have access to such space for the purpose of storing and removing personal property. (v) Parking property The term parking property means any property 90 percent or more of the square footage of which is used for parking or for the ingress or egress of vehicles. (vi) Stadium The term stadium property means any facility (or appurtenant real property) which, during at least 5 days during any calendar year, is used as a stadium or arena for professional sports exhibitions, games, or training. (vii) Disqualified residential rental property The term disqualified residential rental property means