Rule 6-4-a It is illegal participation whan any player, replaced player, or substitute enters during a down.

Play: Prior to the snap, Team B captian realizes that he only has 10 players on the field. He notifies his coach and B11 enters the field of play (is on his side of the ball) just seconds before the snap. Is this illegal participation?

Edit, didn't see it was B.

It wouldn't be any penalty as long as he is on B's side of the neutral zone before the snap. Case book 3.7.5b

[Edited by mmaguth on Aug 28th, 2005 at 10:17 PM]

He didn't enter during the down. The down begins with a legal snap. No foul.

I agree, no foul.

Since it is B no foul. If A, illegal formation. I actually had that this weekend.

Maybe - not enough information to say this is definately a foul on A. We don't know where the entering player was or what he was doing when the ball was snapped.

Agree with Walt. Not enough info. Did A have 7 on the line already? Was the new player moving toward the LOS at the snap? Could be no foul at all.

Wouldnt you have a foul on A entering because he was not within the 9 yard marks after the ready and before the snap?

Indeed not enough info, if the entering player managed to get inside the 9 yard marks and get set with the rest of the team
prior to the snap, then no foul.