The physics programme of high energy e+e- linear colliders relies on the
accurate identification of fermions in order to study in details the profile of
the Higgs boson, search for new particles and probe the multi-TeV mass region
by means of precise electro-weak measurements and direct searches.Comment: 5 pages, to appear on the Proc. of the 9th Int. Workshop on Vertex
Detectors - Vertex 2000, Lake Michigan MI (USA), September 200
