Nuclear dimension and Jiang–Su stability without elementary subquotients

For separable nuclear C${}^{\ast }$-algebras with no nonzero elementary ideal subquotients, finite nuclear dimension is equivalent to Jiang–Su stability. More generally, ${\dim }_{\mathrm{nuc}}(A_0\otimes \mathcal{Z})\le 1$ for every separable nuclear A${}_0$. This proves Robert and Tikuisis's Conjecture (C1) and the nuclear-dimension equivalence in the nonsimple Toms–Winter regularity question.