  We investigate the interaction of Xe with isolated attosecond XUV pulses.
Specifically, we calculate the ion yields and determine the pathways leading to
the formation of ionic charged states up to Xe$^{5+}$. To do so, in our
formulation we account for single-photon absorption, sequential multi-photon
absorption, direct two-photon absorption, single and double Auger decays, and
shake-off. We compare our results for the ion yields and for ion yield ratios
with recent experimental results obtained for 93 eV and 115 eV attosecond XUV
pulses. In particular, we investigate the role that a sequence of two
single-photon ionization processes plays in the formation of Xe$^{4+}$. We find
that each one of these two processes ionizes a core electron and thus leads to
the formation of a double core-hole state. Remarkably, we find that the
formation of Xe$^{5+}$ involves a direct two-photon absorption process and the
absorption of a total of three photons.
