86.1 A racing rule shall not be changed unless permitted in the rule itself or as follows:
(a) Prescriptions of a national authority may change a racing rule, but not the Definitions; the Basic Principles; a rule in the Introduction; Part 1, 2 a 7; rule 42, 43, 47,50, 63.4, 69, 70, 71, 75, 76.3 or 79; a rule of an appendix that changes one of these rules; Appendix H or N; or a rule in a World Sailing Code listed in rule 6.1.
(b) The notice of race or sailing instructions may change a racing rule, but not rule 76.1 or 76.2, Appendix RR, or a rule listed in rule 86.1(a).
(c) Class rules may change only racing rule
42, 49, 51,
52, 53, 54 and 55
86.2 In exception to rule 86.1, World Sailing may in limited circumstances (see World Sailing Regulation 28.1.3) authorize changes to the racing rules for a specific international event. The authorization shall be stated in a letter of approval to the organizing authority and in the notice of race or sailing instructions, and the letter shall be posted on the official notice board.
86.3 If a national authority so prescribes, the restrictions in rule 86.1 do not apply if rules are changed to develop or test proposed rules. The national authority may prescribe that its approval is required for such changes.