Parenthetical main clauses – or not?

Syntactic and semantic characteristics canonically associated with main clauses do not always go together. This paper discusses two puzzling construction types from this perspective: appositive relative clauses (ARCs) and quasi-relatives. I argue that ARCs and appositions are related, and that relativization as such and parenthesis are independent effects. Specifically, an analysis of attributive construal as restrictive relativization of an abstract specific indefinite head explains the syntactically subordinated status of ARCs; on the other hand, the semantic main clause effects attested in ARCs are due to their construal as parenthetical specifications of the anchor, comparable to identificational appositions. Like ARCs, quasi-relatives seem to involve an E-type link with the anchor, but they lack a relative operator, and qualify as main clauses that are either coordinated to the host at the sentence level or inserted as regular parentheticals.