  We present an analysis of ASCA X-ray data of SNR RCW 86. There appears to be
a remarkable spectral variation over the remnant, indicating temperatures
varying from 0.8 keV to > 3 keV. We have fitted these spectra with
non-equilibrium ionization models and found that all regions are best fitted by
emission from a hot plasma underabundant in metals (<0.25 solar), but in some
cases fluorescent emission indicates overabundances of Ar and Fe. The
ionization stage of the metals appears to be far from equilibrium, at some
spots as low as log(n_e t) 15.3 (SI units). We discuss the physical reality of
the abundances and suggest an electron distribution with a supra-thermal tail
to alleviate the strong depletion factors observed. We argue that RCW 86 is the
result of a cavity explosion.
