“…Although there is a vast literature (see Jacod and Rosenbaum, 2013, Li et al, 2016, Li et al, 2019, Hayashi et al, 2011, Martin and Vetter, 2019, and the references therein) on the estimation of volatility functionals of the form ∫ 1 0 g(Σ s )ds where g is a deterministic function, to the best of our knowledge, none of the available results can be applied to our situation, which requires a random transformation of the spot volatility. This situation is investigated in this subsection in the absence of microstructure noise and under the following assumption on the observation times:…”