  The precise determination of the masses of the neutral and charged heavy
Higgs bosons is a crucial input for the study of Supersymmetry and its relation
with cosmology through dark matter. This paper presents a study of e+e- -> HA
and H+H- production at sqrts=3 TeV. The analysis is performed with full
simulation and reconstruction accounting for beamstrahlung effects and the
overlay of gamma gamma -> hadrons events. Results are presented in terms of the
accuracy on the determination of the masses and widths of the heavy Higgs
bosons in two benchmark scenarios.
