What is the Expanded Neural Zone? I'm not a ref so I'm trying to find just a basic definition. As a side not: On play action plays can lineman fake run blocking and the change to pass blocking, if so how far can they go down field and certain ones go farther than others?

NF high school rule.
 

NF high school rule: the neutral zone is the length of the football.

The neutral zone is expanded 2 yards into the defensive side during forward pass plays to allow offensive linemen to block their defensive opponents. Key to remember is that the blockers must be actively blocking a defender. They cannot just fire out two yards and stand there.

Here are fouls that may occur that I've called recently:
1. Offensive guard A53 blocks defensive tackle B76 about 6 yards down the field. Forward pass crosses the neutral zone.
2. Offensive guard A67 is uncovered. On the snap he drifts downfield about 5 yards. Forward pass crosses the neutral zone.

To answer your questions: offensive lineman cannot go beyond their line of scrimmage during a down where a forward pass crosses the neutral zone. If they are beyond the neutral zone they must be blocking a defender and the contact must be within the expanded neutral zone. The expanded neutral zone is 2 yards beyond the normal neutral zone.

Hope you had 1)OPI 2)Ineligible downfield