Uncertainty on the effective temperature as a function of effective temperature (T_eff – log scale). The grey plus signs show the difference (absolute value) between the Node result and the recommended value. The blue line shows the range containing the inner 68.3% of the plus signs, within a T_eff bin. The red line regularises this, taking into account that the uncertainty should increase with T_eff; it is the 1σ uncertainty attributed to T_eff in the recommended parameters.