Results of the exploration of the χ² parametric space carried out with the grid search method, for each of the observed spectral windows. The probability density distribution of the two core fitting parameters (i.e., the EVPA, ϕ, and the fractional polarization, m), corresponding to the χ² scaled by the proper temperature, is shown with six contours located (in peak units) at 0.95, 0.317 (i.e., 1σ), 0.045 (2σ), 0.0027 (3σ), 4σ and 5σ. We note the 180-degree ambiguity of the χ² distribution in the direction of the EVPA.