If D is C+ or D , then we prove that H1(D) is a Hermite regular coherent ring of weak global dimension 2 (the coherence was already proved in [4]). We show: there is a one-to-one equivalence between systems de ned by matrices with entries in H1(D) and coherent H1(D)-modules, coherent H1(D)-modules are stable by elementary algebraic operations, and thus, we can characterize the algebraic propert...