During a dead ball interval, can A42 who was one of the eleven players who participated in the previous play, come off the field, get a drink of water, and go back to the huddle to participate in the next play? Isn't this a dead ball illegal substitution foul since the rule states no player may withdraw and reenter as a substitute during the same dead ball interval unless a penalty is accepted, a dead ball foul occurs, or a time out is taken? Your thoughts would be appreciated.

Illegal - if A42 attempts to come back on the field, inform his coach that he has to stay out for one play. If they refuse to comply, it is illegal substitution and it is a liveball foul simultaneous with the snap. If a charged team time out is granted to either team, A42 may re-enter and play.

This wouldn't be a live ball foul, but a dead ball illegal substitution foul. Why do you say it would be live ball? Is this player allowed to return since he is still a player and was never a replaced player? If he came out by mistake and left 10 players out on the field, and then realized he shouldn't have come out, can he return legally?

Technically, this is legal... Your summary of 3-7-4 is accurate, but the key phrase is "as a substitute"... Since the player in question was never replaced, he is still considered a player, and not a substitute... Therefore, this does not apply...

We had a lengthy discussion about a similar play a while back, but I don't know the link to the thread...

This is not like the Ill. Sub. that is 5 yards if killed before the snap but 15 yards for Ill. Participation after the snap. It is only 5 yard. If you flag it as a dead ball prior to the snap, you have taken away the teams oppurtunity to make themselves legal by making a proper substitution