The table specification indicates that asynchronous circuits exhibit concurrency and causality, and hence their specifications need to reflect these characteristics. A common way is as a timing diagram, seen in Fig. 5d for the C-element, which represents a set of signals and their interactions over time. Each row of a timing diagram represents one signal and how it switches from low to high over time. If a signal displays a change before another signal on another line then this signal must precede the other. An arrow represents that one signal change triggers the change of another. In the C-element diagram, note that X and Y have to precede Z, both in the transition to 1 and down to zero. However, there is no causal dependency between X and Y.