  We present the results of the uniform analysis of 46 XMM-Newton observations
of six BAL and seven mini-BAL QSOs belonging to the Palomar-Green Quasar
catalogue. Moderate-quality X-ray spectroscopy was performed with the EPIC-pn,
and allowed to characterise the general source spectral shape to be complex,
significantly deviating from a power law emission. A simple power law analysis
in different energy bands strongly suggests absorption to be more significant
than reflection in shaping the spectra. If allowing for the absorbing gas to be
either partially covering the continuum emission source or to be ionised, large
column densities of the order of $10^{22-24}$ cm$^{-2}$ are inferred. When the
statistics was high enough, virtually every source was found to vary in
spectral shape on various time scales, from years to hours. All in all these
observational results are compatible with radiation driven accretion disk winds
shaping the spectra of these intriguing cosmic sources.
