  It is possible to distinguish ``intrinsic'' absorption systems (gas clouds
within the quasar environment) from ``intervening'' systems (gas clouds
unrelated to the quasar phenomenon) by considering certain observational
properties. We find that the most direct determinations of the intrinsic nature
of a system are time variability and partial coverage of the background light
source by the absorption region. Both of these conditions are unlikely to occur
in intervening systems. We present Keck and HIRES data which demonstrate both
these phenomena. We also summarize a list of several other observational
properties which appear to be indicative of ``intrinsic'' systems.
