Relative extinction for the dust models of MRN (solid) , WD01-7 (long-dashed; red in electronic version); WD01-21 (short-dashed; green in the electronic version) and WD01-25 (dot-dot-dashed; blue in the electronic version) of interstellar dust. The vertical dotted lines at wavelengths of 912 and 2066 Å, corresponding to 13.6 and 6 eV, show the range of averaging. The horizontal lines show k_FUV for the considered models.