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; a rule in the Introduction; Sportsmanship and the Rules; Part 1, 2 or 7; rule 42, 43.1, 43.2, 69, 70, 71, 75, 76.2 or 79; a rule of an appendix that changes one of these rules; Appendix H or N; or ISAF Regulation 19, 20 or 21.

(b) Sailing instructions may change a racing rule by referring specifically to it and stating the change, but not rule 76.1,
Appendix F, or a rule listed in rule 86.1(a).

(c) Class rules may change only racing rules 42, 49, 50, 51, 52, 53 and 54.

86.2 In exception to rule 86.1, the ISAF may in limited circumstances (see ISAF Regulation 31.1.3) authorize changes to the racing rules for a specific international event. The authorization shall be stated in a letter of approval to the event organizing authority and in the notice of race and sailing instructions, and the letter shall be posted on the eventís official notice board.

86.3 If a national authority so prescribes, these restrictions 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.