  We investigate the possibility of constructing models of R-violating LQD
Yukawa couplings using a single U(1) flavour-symmetry group and supermultiplet
charge assignments that are compatible with the known hierarchies of quark and
lepton masses. The mismatch of mass and current eigenstates inferred from the
known charged-current mixing induces the propagation of strong phenomenological
constraints on some R-violating couplings to many others. Applying these
constraints, we look for flavour-symmetry models that are consistent with
different squark-production hypotheses devised to explain the possible HERA
large-Q^2 anomaly. The e^+ d -> stop interpretation of the HERA data is
accommodated relatively easily, at the price of postulating an extra parity.
The e^+ s -> stop interpretation of the events requires models to have only
small (2,3) mixing in the down quark sector. The e^+ d -> scharm mechanism
cannot be accommodated without large violations of squark-mass universality,
due to the very strong experimental constraints on R-violating operators. We
display a model in which baryon decay due to dangerous dimension-five operators
is automatically suppressed.
