Radio/X‐ray ratio R_X plotted against the radio/optical ratio R_o, for the eight RQQs in our sample. Both R_o and R_X are defined in the text. Filled circles represent objects detected at X‐ray, optical, and radio wave bands, while the open circles with arrows represent the two RQQs that are not detected at X‐ray wavelengths. Errors in R_X may be quite large, perhaps as high as 0.5 dex in individual cases. Diagonal lines indicate optical/X‐ray ratios of 1 and 100, where the ratio is ﹩\nu S_{\nu }( 4400\ \Å ) / F_{\mathrm{X}\,}( 2{\mbox{--}} 10\ \mathrm{keV}\,) ﹩. The RLQs 3C 273 and 3C 454.3 are also plotted, with two values corresponding to total and unresolved (by VLBI) radio flux densities.