  The standard electroweak model with Dirac neutrinos is extended by way of the
principles of electroweak quark-lepton symmetry and weak topological-charge
confinement to account for quark-lepton charge relations which, if not
accidental, are indicative of charge structures. A mixing in quarks and leptons
of underlying integer local charges with integer weak topological charges
associated with an additive group Z_3, fixed by the anomaly cancellation
requirement, is discussed. It is found that the electroweak difference between
topological quarks and leptons is the nonequivalence between the topological
vacua of their weak field configurations, produced by a four-instanton which
carries the topological charge, induces the universal fractional piece of
charge distinguishing quarks from leptons, and breaks the underlying symmetry.
The constituent quarks of the standard model appear as coming from topological
quarks, via the weak four-instanton event. Dual transitions occur for leptons.
It is shown that several other fundamental problems left open in the standard
electroweak model with Dirac neutrinos are solved: the one-to-one
correspondence between quark and lepton flavors, the existence of three
generations, the conservation and ungauging of B-L, the electric charge
quantization, and the confinement of fractional electric charges.
