  In the line-of-sight toward the DO-type white dwarf RX J0503.9-2854, the
density of the interstellar medium (ISM) is very low, and thus the
contamination of the stellar spectrum almost negligible. This allows us to
identify many metal lines in a wide wavelength range from the extreme
ultraviolet to the near infrared. In previous spectral analyses, many metal
lines in the ultraviolet spectrum of RX J0503.9-2854 have been identified. A
complete line list of observed and identified lines is presented here. We
compared synthetic spectra that had been calculated from model atmospheres in
non-local thermodynamical equilibrium, with observations. In total, we
identified 1272 lines (279 of them were newly assigned) in the wavelength range
from the extreme ultraviolet to the near infrared. 287 lines remain
unidentified. A close inspection of the EUV shows that still no good fit to the
observed shape of the stellar continuum flux can be achieved although He, C, N,
O, Al, Si, P, S, Ca, Sc, Ti, V, Cr, Mn, Fe, Cr, Ni Zn, Ga, Ge, As, Kr, Zr, Mo,
Sn, Xe, and Ba are included in the stellar atmosphere models. There are two
possible reasons for the deviation between observed and synthetic flux in the
EUV. Opacities from hitherto unconsidered elements in the model-atmosphere
calculation may be missing and/or the effective temperature is slightly lower
than previously determined.
