Timing constraints are based on events. An event is an occurrence of one of the following actions:

In addition, events can be referred to by their type, without giving a concrete name:

When specifying events of interest, the states in which they may be observed can also be given: in state States event

Timing constraints are defined as rules and specify admissible intervals between observed events. There are five types of timing rules:

States is a list of states, e.g., "on, off"; the "in state" part is optional.

For an interval there are three possible forms: