Add the opinion number or the year

Error²Federal courts, Illinois courts21st and 22nd editions

A formal or informal ethics opinion is identified by three elements: the issuing body, the opinion's own number, and the year it issued, that year in a parenthetical.¹

1. 1R. 12.9.5 ABA Code of Professional Responsibility and Opinions on Ethics.
2. 2An error: the rule in note 1 allows one form, and this is not it.