  Black hole accretion disks appear to produce invariably plasma outflows that
result in blue-shifted absorption features in their spectra. The X-ray
absorption-line properties of these outflows are quite diverse, ranging in
velocity from non-relativistic ($\sim 300$ km/sec) to sub-relativistic ($\sim
0.1c$ where $c$ is the speed of light) and a similarly broad range in the
ionization states of the wind plasma. We report here that semi-analytic,
self-similar magnetohydrodynamic (MHD) wind models that have successfully
accounted for the X-ray absorber properties of supermassive black holes, also
fit well the high-resolution X-ray spectrum of the accreting stellar-mass black
hole, GRO J1655-40. This provides an explicit theoretical argument of their MHD
origin (aligned with earlier observational claims) and supports the notion of a
universal magnetic structure of the observed winds across all known black hole
sizes.
