From left to right and top to bottom: Stokes I, Q, U and V profiles (dots) of the Si i line normalized to the continuum, and best fits (solid line) using a two-component SIR inversion. The profiles correspond to [x,y] = [201, 194] (area 4 in Fig. 5). The single-component fit (i.e., standard fit) is shown in the dashed lines for comparison and clearly does a worse job at fitting Stokes V. The physical parameters inferred from the two-component inversion are: v₁ = 0.3  ±  0.2 km s^-1, B₁ = 1001  ±  68 G, γ₁ = 67°  ±  3°, φ₁ = 114°  ±  2°, f ~ 0.94 for the standard component and v₂ = 11  ±  2 km s^-1, B₂ = 1424  ±  300 G, γ₂ = 23°  ±  20°, φ₂ = 81°  ±  51°, f ~ 0.06 for the magnetic one. The inferred stray-light is α ~ 5%. The uncertainties associated to the parameters of the second component were obtained with SIR and verified with the sensitivity analysis explained at the end of Sect. 4.2.