  Lorentz and CPT symmetry have been tested at high precision in numerous
experiments. A general theoretical framework incorporating possible Lorentz and
CPT violation in an extension of the standard model of particle physics has
been developed. In this framework, analyses of several precision experiments
have been performed to find unsuppressed symmetry-violating signals. This paper
discusses features of the theory, presents results for trapped-particle
systems, and reports bounds from recent experiments.
