Transmission line
Transmission line - a set of linear paths of transmission systems and (or) typical physical circuits having common linear structures, their service devices, and the same propagation medium within the scope of service device operation.
Notes. 1. Transmission lines are named depending on:
the primary network to which they belong: trunk, intra-zone, local;
the propagation medium, for example, cable, radio relay, satellite.
2. Transmission lines consisting of a sequential connection of transmission lines with different propagation media are assigned the name "combined."
Source: ORDER OF GOSTELKOM OF RUSSIA dated 28.09.1999 No. 48
"ON APPROVING STANDARDS FOR ELECTRICAL PARAMETERS OF DIGITAL CHANNELS AND TRUNKS OF SATELLITE TRANSMISSION SYSTEMS"