Use Feathers. A Feather, sometimes called a 'continuation' or 'fly-off', is a smart symbol that indicates that a cable segment in one place continues somewhere else, either within the current drawing or in another drawing. Cable segments matched with paired Feathers mean that 2 disparate Cable segments can be treated as a single physical Cable for the purposes of the Cable Schedule.

For a full walkthrough, see the video — Feathers — in the Movies section.