Whose Clauses | Grammar Quizzes
https://www.grammar-quizzes.com/clauses-3.htmlA nonidentifying clause (non-restrictive clause) adds extra information about a noun already identified by other means, for example, by name, by shared knowledge or context. The clause, a comment, is set off with commas (before and, if necessary, after the clause). It is also called nonrestrictive, nonessential, or unnecessary clause.