  The physics behind the ionization structure of outflows from black holes is
yet to be fully understood. Using archival observations with the Chandra\HETG
gratings over the past two decades, we measured an absorption measure
distribution for a sample of outflows in nine active galaxies (AGNs), namely
the dependence of outflow column density, $N_H$, on the ionization parameter,
$\xi$. The slope of $\log(N_H)$ vs. $\log\xi$ is found to be between 0.00 and
0.72. We find an anti-correlation between the log of total column density of
the outflow and the log of AGN luminosity, and none with the black hole mass
and accretion efficiency. A major improvement in the diagnostics of AGN
outflows will potentially occur with the launch of the XRISM/Resolve
spectrometer. We study the ability of Resolve to reveal the outflow ionization
structure by constructing the absorption measure distribution from simulated
Resolve spectra, utilizing its superior resolution and effective area. Resolve
constrains the column density as well as HETG, but with much shorter
observations.
