Center-to-limb variation (CLV) of the Stokes I (left panel) and Q/I (right panel) signal at the wavelength λ₀ at the D₂ line center. The colored curves correspond to the results of calculations in which 15 G magnetic fields of various orientations were considered, including a microturbulent and isotropic field (green curve) and deterministic magnetic fields, both vertical (θ_B = 0°; red curve) and horizontal and contained in the plane defined by the local vertical and the LOS (θ_B = 90°, χ_B = 0°; blue curve). The CLV obtained in the absence of a magnetic field (black curve) is also shown. The thin black dashed line indicates Q/I = 0.