(Survey 2 − Survey 1)/ 2 consistency test result from the ds1 × ds2 cross-spectra at 100, 143, and 217 GHz, with the f_sky ≃ 0.30 mask derived from that used in the primary cosmological analysis (see text). Left: the residual signal in each bandpower up to the highest multipole used in the likelihood code (Planck Collaboration XV 2014). For clarity, the bins used in the likelihood analysis are grouped in sets of four for ℓ > 60 and sets of eight for ℓ > 1250. We show in each bin the variance of the C_ℓ distribution from the simulations. Note that the amplitude of the residual signal is under the binned sample variance envelope expected for the f_sky ≃ 0.30 mask (shown in black) up to ℓ ~ 1000 at all three frequencies. Right: zoom-in on the low-ℓ part of the spectrum, showing that although the difference test failures are highly significant at these scales, their amplitudes at all three CMB frequencies are less than about 0.5 μK² for all multipoles up to ℓ = 200, which is a tiny fraction of the binned sample variance at these scales.