Reconstructed power spectra applied to the Planck 2015 data using 12 knots (with positions marked as Δ at the bottom of each panel) with cubic spline interpolation. Mean spectra as well as sample trajectories are shown for scalars and tensors, and ± 1σ and ± 2σ limits are shown for the scalars. The fiducial tensor spectrum corresponds, arbitrarily, to r = 0.13. Top: uniform prior, 0 ≤ r ≤ 1. Middle: fixed, r = 0.1. Bottom: fixed, r = 0.01. Data sets: Planck TT+lowP+BAO+SN+HST+z_re > 6 prior. D_rec is the comoving distance to recombination.