  In this paper we revisit the Restricted Additive Schwarz method for solving
discretized Helmholtz problems, using impedance boundary conditions on
subdomains (sometimes called ORAS). We present this method in its variational
form and show that it can be seen as a finite element discretization of a
parallel overlapping domain decomposition method defined at the PDE level. In a
fourthcoming paper, the authors have proved certain contractive properties of
the error propagation operator for this method at the PDE level, under certain
geometrical assumptions. We illustrate computationally that these properties
are also enjoyed by its finite element approximation, i.e., the ORAS method.
