Planck constraints on the spectral parameters n_s,dn_s/ dlnk, and r. We compare constraints computed with the second-order slow-roll approximation, starting from flat priors on the HFF parameters at the pivot scale (ϵ₁,ϵ₂,ϵ₃), with those obtained directly from n_s,dn_s/ dlnk, and r. In the latter case we enforce the second-order consistency conditions for the tensor-to-scalar ratio and for the running of the tensor spectral index.