  Classical T Tauri stars show a plethora of in- and outflow signatures in a
variety of wavelengths bands. In order to constrain gas velocities and
temperatures we analyse the emission in the hot ion lines. We use all available
archival FUSE spectra of CTTS to measure the line widths, fluxes and shifts and
complement this sample with HST/GHRS and HST/STIS data. We present theoretical
estimates for temperatures reached in possible emission models like jets,
winds, disks and accretion funnels and look for correlations with X-ray lines
and absorption properties. We find line shifts in the range from -170 km/s and
+100 km/s. Most linewidths exceed the stellar rotational broadening. Those CTTS
with blue-shifted lines also show excess absorption in X-rays. CTTS single out
from MS stars by their large ratio of the O VII to O VI luminosities. No single
emission mechanism can be found for all objects. The properties of those stars
with blue-shifted lines are compatible with an origin in a shock-heated
dust-depleted outflow.
