Use a short form naming the authority

Error²Federal courts, Illinois courts21st and 22nd editions

“Id.” points at the authority cited immediately before it, so it is ambiguous where that citation named more than one authority.¹

1. 1R. 4.1 “Id.”; B4 Short Citation Forms; B10.2 Short Form Citation.
2. 2An error: the rule in note 1 allows one form, and this is not it.