  A general Lorentz-violating extension of the minimal SU(3) x SU(2) x U(1)
standard model is described, including both CPT-even and CPT-odd terms. Some
theoretical properties and experimental implications are given. The extension
can be regarded as a low-energy limit of a physically relevant
Lorentz-covariant fundamental theory in which spontaneous Lorentz violation
occurs.
