In CID to WID interconnect diagrams, when you delete a fiber segment in a Circuit diagram, you are prompted to delete the corresponding Wiring design fiber.

In the figure below, the circuit segment being deleted disconnects a port. As a result, not all the ports for the circuit_id are connected. You are prompted to delete the Wiring design fiber.

In the figure below, the circuit segment being deleted breaks the network into 2 separate networks. Both networks have the same circuit_id. All ports are still connected, therefore, you are not prompted to delete a Wiring fiber.