Ionization parameter ξ against the ionizing luminosity L in units of the luminosity of the L02 observation L₀ for components A and B (top panels), C and D (middle panels), and E and F (bottom panels). Black filled circles represent the LETGS observations, red crosses the HETGS observations, and green filled triangles the RGS observations. The dotted horizontal line indicates no response to continuum changes, while the dashed diagonal shows ξ proportional to L and indicates instantaneous response to variations in the ionizing flux.