[en] The correlation between linear polarization of one γ-ray quantum and polarization of the next γ-ray quantum emitted in a cascade from an oriented nucleus is discussed. This correlation forms the basis for developing the PPCO method which, in principle, can determine spins, parities and multipolarities. The method is particularly useful when γ rays are produced in heavy ion reactions, ensuring a high spin alignment. The paper presents an experimental test of the PPCO method and the results suggest, that this method can be applied with success in modern γ-ray spectroscopy in which a large number of detectors are sensitive to the polarization (e.g. the CLOVER detectors). When this method is combined with an angular correlation analysis, the number of the possibilities concerning spins, parities and multipolarity sequences can be reduced significantly