“…Before we proceed, let us note that for a function k ∈ Ḃs p,q (R, L ∞ (R)), it need not be the case that the decomposition k = j∈Z k j holds (compare to the scalarvalued failure of such a decomposition, as detailed in [21, Chapter 3, Proposition 4]). Despite this, it follows from an obvious modification of [19,Lemma 4.1.4] that if k ∈ L ∞ (R 2 ), then there exists a function c ∈ L ∞ (R), such that k(t, s) = c(t) + j∈Z (k j (t, s) − k j (t, 0)) , for all t, s ∈ R 2 , and such that c ∞ k ∞ + |k| Ḃs p,q (R,L∞(R)) . Finally, we may state our strengthening of [5,Theorem 9.2].…”