[Cyrien]

I have always just refered to it as a sector or grid or square when talking about it. As for any actual distance it may represent... well there isn't one. This is most apparant when looking at battles around planets/stars etc. The differences in the number of squares different planets take up vs the number of squares a star takes up make it clear that they don't clearly represent any set distance. It is just a way to contain the combat in an effective system.