English has a distinction between restrictive relative clauses (which provide information necessary for identifying the referent, or which restrict the set of possible referents) and non-restrictive relative clauses (which merely provide additional background information on an already-determined referent set). But Russian, for example, does not bother with that distinction. So, while I have no idea what the distribution of this feature in natlangs generally is (there doesn't seem to be a WALS feature for it), there is clearly variation. In contrast, there is no way to distinguish restrictive vs. non-restrictive adjectives (apart from relativizing a predicate adjective clause) in English. So, now I'm wondering, is there any natlang precedent for a regular (either syntactic or morphological) distinction between restrictive and non-restrictive attributive adjectives? If not, is there a conlang precedent known to the List? -l.