This is an informal attempt to provide a simple description of sentences (1) sinejas', mal'6ik vySel 'laughing, boy left' and (2) smejuscijsja mal'c'ik vyel 'the laughing boy left.' Sentences (1) and (2) are each similar to (3) mal'Zik, kotoryj smejalsfa, vysel, which, as a written sentence at least, is ambiguous. The meaning is either (a) the boy, who was laughing, left, where clause is nonrestrictive, or (b) the boy who was laughing left, where clause is restrictive. The nonrestrictive clause of sentence (3a) is close in meaning to smnejas' of sentence (1), while restrictive clause of sentence (3b) is close to smejuscijsja of sentence (2). This correspondence is more clearly seen in case of an antecedent noun which does not admit both types of relative clauses, e.g., a proper noun. Smejas', Ivan vysel correlates with grammatical (if awkward) Ivan, kotoryj smejalsfa, vySel, while unacceptability of *smejus.Jijsfa Ivan vysel mirrors impossibility of a restrictive relative clause following Ivan. Let us formalize semantic closeness of smnejas' and nonrestrictive relative clause on one hand and of smejuscijsja and restrictive relative clause on other by positing a single underlying representation for (1) and (3a) and another for (2) and (3b). And from these underlying representations let us derive formal differences between (1) and (2). A significant formal difference between sentences (1) and (2) is comma intonation which sets smejas' off from rest of sentence. Soviet grammarians call this comma intonation (obosoblenie). Isolation is a necessary feature of (1) and necessarily absent from (2): *smejas' mal'cik vysel is not a sentence of Russian, nor is *smejuscijsja, mal'cik vysel. Are there features of (3a) corresponding to comma intonation of (1) which might justify positing isolation as a feature of underlying representation which it is proposed that they share? As spoken sentences (3a) and (3b) are not necessarily homophonous. It is possible that a longer, or in some way different, pause can separate noun from relative clause in (3a) compared to (3b).x Be that as it