  We quantitatively analyze a quark-lepton flavour model derived from a
six-dimensional supersymmetric theory with $SO(10)\times U(1)$ gauge symmetry,
compactified on an orbifold with magnetic flux. Two bulk $\mathbf{16}$-plets
charged under the $U(1)$ provide the three quark-lepton generations whereas two
uncharged $\mathbf{10}$-plets yield two Higgs doublets. At the orbifold fixed
points mass matrices are generated with rank one or two. Moreover, the zero
modes mix with heavy vectorlike split multiplets. The model possesses no
flavour symmetries. Nevertheless, there exist a number of relations between
Yukawa couplings, remnants of the underlying GUT symmetry and the wave function
profiles of the zero modes, which lead to a prediction of the light neutrino
mass scale, $m_{\nu_1} \sim 10^{-3}$ eV and heavy Majorana neutrino masses in
the range from $10^{12}$ GeV to $10^{14}$ GeV. The model successfully includes
thermal leptogenesis.
