“…The construction method is along the lines of [18], and we may also carry it out using the volume-controlled Lipschitz maps. If one compares the construction in [32] with that in [18], one sees that differences occur only near the boundary ∂U : more precisely, the approximate smoothed mean curvature vector is damped near the portion of Γ 0 close to ∂U , and there is another step in each epoch -a Lipschitz retraction step (see [32,Section 2.6]). Hence, the proof of the present paper works with no essential change away from ∂U , and (2.14) holds for φ ∈ C 1 c (U × R + ); since the formula does not involve ∇φ, by approximation, the same formula holds even for φ ∈ C 1 (clos U × [0, T ]) for arbitrary T > 0.…”