  It is common to assume that all narrow absorption lines (NALs) at extreme
high-velocity shifts form in cosmologically intervening gas or galaxies
unrelated to quasars. However, previous detailed studies of individual quasars
have shown that some NALs at these large velocity shifts do form in high-speed
quasar ejecta. We search for extreme high-velocity NAL outflows (with speeds
$\sim$0.1-0.2c) based on relationships with associated absorption lines (AALs)
and broad absorption-line (BAL) outflows. We find that high-velocity NALs are
strongly correlated with AALs, BALs, and radio loudness, indicating that a
significant fraction of high-velocity systems are either ejected from the
quasars or form in material swept up by the radio jets (and are not unrelated
intervening gas). We also consider line-locked C IV doublets as another
indicator of high-velocity NALs formed in outflows. The fact that line-locked
NALs are highly ionized and correlated with BAL outflows and radio-loud quasars
implies that physical line locking due to radiative forces is both common and
real, which provides indirect evidence that a significant fraction of
high-velocity NALs are intrinsic to quasars.
