  We show that invaluable information on the structure of quasar outflows can
be obtained by considering microlensing (ML) induced variability of absorption
line troughs in lensed quasars. Depending on the structure and geometry of the
outflowing gas, such extrinsic line variability can be manifested as changes to
the equivalent width of the line as well as line profile distortions. Here we
consider several physically distinct outflow models, having very similar
spectral predictions, and show how ML induced absorption line variability can
be used to distinguish between them. The merits of future systematic studies of
these effects are exemplified.
