  The `shock in jet' model for cm-waveband blazar variability is revisited,
allowing for arbitrary shock orientation with respect to the jet flow
direction, and both random and ordered magnetic field. It is shown that oblique
shocks can explain events with swings in polarization position angle much less
than the 90 deg. associated with transverse structures, while retaining the
general characteristics of outbursts, including spectral behavior and level of
peak percentage polarization. Models dominated by a force-free, minimum energy
magnetic field configuration (essentially helical) display a shallow rise in
percentage polarization and frequency dependent swing in polarization position
angle not in agreement with the results of single-dish monitoring observations,
implying that the field is predominantly random in the quiescent state.
Outbursts well-explained by the `shock in jet' model are present during
gamma-ray flaring in several sources, supporting the idea that shock events are
responsible for activity from the radio to gamma-ray bands.
