The secondary division of the universe. Each galaxy contains 499 systems. The second number in any set of coordinates denotes the system in which the planet is located. When you use galaxy view you view one system at a time.
The look of a system and its planets repeats every 40 systems. E.g. Planet 2:40:8 looks like planet 2:80:8 and planet 2:80:2 looks like planet 2:120:2. But this is not the same on 2:180:2 because it resets itself.