  We prove the following two results
  1. For a proper holomorphic function $ f : X \to D$ of a complex manifold
  $X$ on a disc such that $\{df = 0 \} \subset f^{-1}(0)$, we construct, in a
functorial way, for each integer $p$, a geometric (a,b)-module $E^p$ \
associated to the (filtered) Gauss-Manin connexion of $f$.
  This first theorem is an existence/finiteness result which shows that
geometric (a,b)-modules may be used in global situations.
  2. For any regular (a,b)-module $E$ we give an integer $N(E)$, explicitely
given from simple invariants of $E$, such that the isomorphism class of
$E\big/b^{N(E)}.E$ determines the isomorphism class of $E$.
  This second result allows to cut asymptotic expansions (in powers of $b$) \
of elements of $E$ without loosing any information.
