The fourth planet of the secondary of the Nivenia System, B4 is half of the local transport hub of the secondary's ringworlds and population in the Nivenian Empire, with the other half on B5.1. This division was made partly to combat the almost three days of light-lag accompanying communications between the stars of the binary. As such it is sometimes granted some special privileges by the government on Nivenia Prime.
B4 is covered by over a thousand kilometers of salty ice, and is one of the sources of sodium and potassium in the Nivenian Empire, and producing fertilizer. Its main products, though, are administration and bureaucracy.
B4 is a major spaceport, and is the center of transport for the secondary star of the system.