The relative clause resisting unification

Cinque (2020) presents a unified theory positing that various types of relative clauses (RCs) originate from a single, double-headed universal structure via raising or matching. The Frame Noun-Modifying Clause (FRC) as described and analyzed by Matsumoto et al. (2017a, 2017b) presents a significant challenge to Cinque's framework, as it does not conform to any of Cinque's identified RC types, which include amount RCs, kind(-defining) RCs, restrictive RCs and non-restrictive RCs. The FRC eludes derivation via the proposed matching or raising mechanisms. Determining the semantic link between the head noun and the FRC, as well as its external merger position, remains elusive. One might suggest that inserting additional material into the FRC, which incorporates a plausible internal head, could clarify their connection. This approach falls short of providing a systematic and coherent syntactic criterion, relying instead on semantic intuition that lacks operational reliability.