The word conditional is used in a variety of senses in the literature. We avoid its use altogether, except when describing the work of other authors who use it in specialized senses: for example, the conditional actions and conditioning of Peot and Smith [1992]. We use the term contingency plan to refer to a plan that contains actions that may or may not actually be executed, depending on the circumstances that hold at the time. We use the term context-dependent to refer to action effects that depend on the context in which the action is performed.