  Appreciable CP Asymmetries (~ 10%) can arise in the reaction e+ e- -> t bar-t
Z already at TREE-LEVEL in models with two Higgs doublets. For a neutral Higgs
particle, h, with a mass in the range 50 GeV < m_h < 400 GeV, it may be
possible to detect a 2-3 sigma CP-odd effect in e+ e- -> t bar-t Z in ~ 1-2
years of running of a future high energy e+e- collider with c.m. energies of ~
1-2 TeV and an integrated luminosity of 200-500 inverse fb.
