From Longman Dictionary of Contemporary Englishnon-restrictiveˌnon-reˈstrictive adjective technical SLGa non-restrictive relative clause gives additional information about a particular person or thing rather than saying which person or thing is being mentioned. For example, in the sentence ‘Perry, who is 22, was arrested yesterday’, the phrase ‘who is 22’ is a non-restrictive clause.
Examples from the Corpus
non-restrictive• Thus, in the first case but not in the second, the adjective is non-restrictive.• In fact, it seems impossible to find examples of associatives which are non-restrictive, and this is not accidental. 