– 27 – Fig. 6.— Left panel: mid-IR color-color distribution of the Photometry Group 3, Variability Level 2 sources selected as AGNs based on their X-ray (squares), radio (triangles), or 24 µ m emission (dots). The contours and selection regions are the same as in Figure 5. Right panel: histograms of the fraction of the Photometry Group 2 X-ray (solid), 24 µ m (dashed), and radio (dotted) sources identified as Variability Level 2 variables as a function of [3 . 6] − [4 . 5] color.