What does it mean - It's line ball.?

Line ball means its questionable
outside the line, definitive and not good
inside the line, also definitive, and its all good
Line ball its not as black and white

Probably NOT a Singles and Dating question... unless you're naked with the opposite sex OR SAME SEX, if that's your thing.
(In which case, I DON'T WANT TO KNOW, what "Line Ball" means)