Disentangling fundamental MSSM Parameters: Light Gaugino/Higgsino System

In order to reveal the underlying structure of Supersymmetry one has to determine the low–energy parameters without assuming a specific SUSY breaking scheme. In this paper we show a procedure how to determine M_1, \Phi_{M_1}, M_2, \mu, \Phi_{\mu} and \tan\beta even in the case when only light charginos \tilde{\chi}^{\pm}_1 and neutralinos \tilde{\chi}^0_1, \tilde{\chi}^0_2 would be accessible at the first stage of a future Linear Collider with polarized beams.