Absolute photoionization cross-section measurements for a mixture of ground and metastable states of ${\mathrm{Xe}}^{4+}$, ${\mathrm{Xe}}^{5+}$, and ${\mathrm{Xe}}^{6+}$ are reported in the photon energy range of $4d\ensuremath{\rightarrow}nf$ transitions, which occur within or adjacent to the $13.5\phantom{\rule{0.3em}{0ex}}\mathrm{nm}$ window for extreme ultraviolet lithography light source development. The reported values allow the quantification of opacity effects in xenon plasmas due to these $4d\ensuremath{\rightarrow}nf$ autoionizing states. The oscillator strengths for the $4d\ensuremath{\rightarrow}4f$ and $4d\ensuremath{\rightarrow}5f$ transitions in ${\mathrm{Xe}}^{q+}$ $(q=1--6)$ ions are calculated using nonrelativistic Hartree-Fock and random phase approximations. These are compared with published experimental values for ${\mathrm{Xe}}^{+}$ to ${\mathrm{Xe}}^{3+}$ and with the values obtained from the present experimental cross-section measurements for ${\mathrm{Xe}}^{4+}$ to ${\mathrm{Xe}}^{6+}$. The calculations assisted in the determination of the metastable content in the ion beams for ${\mathrm{Xe}}^{5+}$ and ${\mathrm{Xe}}^{6+}$. The experiments were performed by merging a synchrotron photon beam generated by an undulator beamline of the Advanced Light Source with an ion beam produced by an electron cyclotron resonance ion source.