To kinda piggy back on infield fly....

[sp279]

NFHS rules.....season's not for a few months yet but wanna get this right.

Last season, lot of coaches complained it was not an "Infield fly" because the arc of the ball was not a straight up, then down. Most times doing JV or lower, it don't go that high anyway.

So....to call it right, what is the correct "arc"? Where is that "line"? This is even more accentuated when there's 2 outs, a player lets it fall to the ground, I've called the batter out, there's a runner in scoring position at 3rd and boy do you hear it.
Thoughts?
Thanks.