Use plain punctuation after “Id.”

Error²Federal courts, Illinois courts21st and 22nd editions

“Id.” takes a single period and runs straight into its pincite, with the word “at” lowercase and no comma between.¹

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