2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/135957We show that every sum system is divisible. Combined with B. V. R. Bhat and R. Srinivasan's result, this shows that every product system arising from a sum system (and every generalized CCR flow) is either of type I or type III. A necessarily and sufficient condition for such a product system to be of type I is obtained.22 pagesOperator AlgebrasFunctional Analysis46L55;47D03text