Comparison of our weighted oscillator strengths for Kr iv–vii (from top to bottom) to those of Bredice et al. (2000), Raineri et al. (2012), Pagan et al. (1996), and Liang et al. (2013), respectively. Left panel: comparison of weighted oscillator strengths. Right panel: ratio of weighted oscillator strengths over wavelength. The wavelength ranges of our FUSE and HST/STIS spectra are marked. The larger, red symbols refer to the lines identified in RE 0503−289 (see Figs. 5 and 8).