Interference?

[tcannizzo]

2) The ball is neither a Foul Ball or a Fair Ball just prior to the contact between B/R-1 and F3 who was attempting to make a play on the Ball.

There are only two definitions in the books that I own, a fair ball and a foul ball. What is the third definition? And what book is it in?

4) B/R-1 has committed Interference with F3. The Ball becomes Dead immediately. B/R/-1 is out because of committing Interference. All runners return to the bases they occupied at the time of the B/R-1's Interference.

The definition of "play" includes an attempt to retire an offensive player.
What "play" would occur by touching a ground ball in foul territory?