Fair foul question

[bossman72]

Well FED clears this up with the imaginary fair/foul line running from first to third. If it hits past that, it's fair.

OBR, some would say, that the imaginary line to mean 'past' is if you drew a line from first base to second base (that's the 'past first' line) and drew one from third to second (that's the 'past third' line). However, there really hasn't been an official interpretation stating this.