One real-world example of relay logic is in elevator control systems. In elevator control, relays are used to manage the opening and closing of doors, floor selection, and movement direction.

Scope: This Standard sets forth principles governing the formation of graphical symbols for logic diagrams in which connections between symbols are generally shown with lines. Definitions of logic ...

An international language by which it is possible to determine the functional behavior of a logic or circuit diagram with minimal reference to supporting documentation is defined; as such, it is ...

For example, a rung may contain a switch, a contact, and a coil, which form a series connection. The logic of the circuit can be read from left to right, following the flow of current.