  The coset spaces E$_8$/SO(10)$\times$H$_F$ allow complex structures which can
account for three quark-lepton generations including right-handed neutrinos. We
show that in the context of supersymmetric SO(10) gauge theories in 6
dimensions they also provide the Higgs fields which are needed to break the
electroweak and ${B-L}$ gauge symmetries, and to generate small neutrino masses
via the seesaw mechanism.
