The Beam line is the designation for a multitude of space structures the Gammetans are designing to increase the supply line length of the Navy.
Beam lines will be small structures (around 10 meters), and will just consist of a lot of small structures placed in a line in space between one planet and another. Each structure will contain: some sensors for early-warning; a small shield generator for holding off attackers for a while; engines and hyperdrive for navigation; an automatically triggered communicator if unknown vessles are detected; a beam line emitter to reduce the energy cost of beaming between structures; a small power generator; and, of course, a beaming system. They need no inside structure or life support, for nothing will get inside the structure. Cargo will be beamed, literally, inside of the beaming system onboard the first structure in the line. By default, based on what direction the beam was received, that cargo, before rematerializing, will be beamed in to the next one, and so on, until it reaches the last one. At each end of the line, several sensors are dutied to monitor what is beamed in to the module, then beam it to somewhere based on what it is, such as a person or, in this case, a metal.