"Floating point" Well, floating point, was just a fast translation of the "concept", which is about how alexh describes it! I don't think it is a official term, Floating area might be better... Instead of thinking just in distance in relation to being placed in the middle of the court, this area takes into account time, both time for you to reach the corners, but also the time for the shuttle to travel from the opponents racket to wherever it is suppose to travel! Also, it is common that players do move faster forward than backward, therefore the base in general is closer to the back court. Therefore the exact mathematically measurement of the "middle" of the court, we/I don't really use that.