  The clockwork mechanism is a means of naturally generating exponential
hierarchies in theories without significant hierarchies among fundamental
parameters. We emphasize the role of interactions in the clockwork mechanism,
demonstrating that clockwork is an intrinsically abelian phenomenon precluded
in non-abelian theories such as Yang-Mills, non-linear sigma models, and
gravity. We also show that clockwork is not realized in extra-dimensional
theories through purely geometric effects, but may be generated by appropriate
localization of zero modes.
