Use round parentheses for the year

Error²Federal courts, Illinois courts21st and 22nd editions

A Canadian citation gives its two years different delimiters: the reporter year keeps the square brackets, and a differing year of decision leads the citation in round parentheses.¹

1. 1T2.6 Canada.
2. 2An error: the rule in note 1 allows one form, and this is not it.