Among certification techniques, those based on the violation of Bell
inequalities are appealing because they do not require assumptions on the
underlying Hilbert space dimension and on the accuracy of calibration methods.
Such device-independent techniques have been proposed to certify the quality of
entangled states, unitary operations, projective measurements following von
Neumann's model, and rank-one positive-operator-valued measures (POVM). Here,
we show that they can be extended to the characterization of generalized