Illustration of a composite model of the bump height based on DIBs and the UV ratio EW(5780)/EW(5797). (a) Bump height and UV ratio 5780/5797. (b) Composite power-law model (Eq. (2)) based on the 5850 Å DIB and the UV ratio, for all stars with DIB 5850 Å data (55 targets). (c) Same as panel b, for a model based on flag F=1 stars only. (d) Composite power-law model (Eq. (2)) based on DIB 5780, DIB 5850, and the UV ratio, adjusted on flag F=1 stars (89 targets). Flag F=0 stars are in red, Flag F=1 stars in violet. In panels b, c, and d, the y = x curves are superimposed.