Dispersion-corrected δOPD^meas plotted against the projected baseline component B_∥ for the MJD = 60918 A–B sequence. B_∥ is computed from the (u, v) coordinates via B_∥ = (uΔα + vΔδ)/∣θ∣, where Δα and Δδ are the east and north components of θ = r_A − r_B. Each color denotes a baseline (W2 reference), and the black line is the best-fitting linear relation. For a fixed separation vector, δOPD scales linearly with B_∥ (the component of the projected baseline along the A–B separation; using ∣B∣ would not yield a linear relation), so the alignment of the multibaseline points provides a direct consistency check on the OPD sign conventions and time matching. The residual scatter about the fit reflects the ∼0.37 μm effective OPD noise used in the bootstrap uncertainty estimate.