Locations are defined by a set of coordinates like the following:
3:233:5
The first number specifies the galaxy. The second number specifies the solar system. The third number specifies the planet location (“slot”) in the solar system. So in the above example, the location referred to is located in Galaxy 3, Solar System 233, Slot 5.
Hint: In a solar system, planet slot 1 is closest to the sun, while slot 15 is furthest from the sun. This is important later when deciding where to put your colonies. Hotter planets can produce solar power more cheaply, while colder planets can produce deuterium more efficiently. Average planet size (its number of available fields) also varies with slot location; slot 8 planets generally have a larger field count, while those closer or farther from the sun tend to be small