Mean spline to quadratic function ratio ⟨ R ⟩ (as defined in Eq. (1)) vs. the angular distance Δθ from the associated R08 object, for all unambiguous UKIDSS sources detected (left panel), and for the sources from the validation sample (right panel), which are color-coded according to their visual evaluation of good (pale sky blue) or bad (red) match with the MIR SED. The limits on ⟨ R ⟩ and Δθ defining the quantitative criteria of Eq. (2) are indicated as dashed lines on both panels.