  We present soft X-ray spectroscopy of the black hole binary LMC X-3 from the
XMM-Newton Reflection Grating Spectrometer. The observations span the full
range of spectral states seen in LMC X-3. The spectra are completely dominated
by continuum emission, and the neutral absorbing column measured from the O I
edge (NH = 3.8 +0.8 -0.7 10^20 cm^-2) is consistent with the Galactic
interstellar column density towards LMC X-3. We find no evidence for
variability of the neutral absorbing column. We also constrain the ionized
column density using the upper limits to the equivalent width of the O II - O
VIII K-shell resonance lines: we find that the equivalent hydrogen column
density of gas in which O is partially ionized is < 8 10^20 cm^-2. From this
upper limit we can rule out a line driven stellar wind as the power source for
the X-ray emission of LMC X-3 except when it is faint. At wavelengths longward
of the peak emission the spectral shape is well described by a
multi-temperature disk-blackbody spectrum; the powerlaw component which
dominates at shorter wavelengths does not continue longward of the
disk-blackbody peak. This implies that the multi-temperature disk-blackbody
component supplies the seed photons which are Compton upscattered in the hot
corona, consistent with the standard paradigm for black hole X-ray binary
spectral states.
