[APG]

For the NFL:

• Must be 7 on the line of scrimmage
• Players on the end of the line must be an eligible receiver
• All players between players on the end of the line must be ineligible receivers
• All players must be inbounds
• All players eligible by number (1-49 and 80-89) must be in eligible positions (at the end of the line or in the backfield) and all players ineligible by number (50-79 and 90-99) must be in positions that wouldn't make them eligible (unless a player reports as eligible or ineligible).
• If the offense shifts, they must present a legal formation at the end of every shift.

You can find the rule book and case book at www.nfl.com/rulebook

NCAA:

• All players inbounds
• All players are either linemen or are in the backfield
• At least 5 linemen numbers from 50-79 (except for a snap from a field goal or punt)
• No more than 4 players in the backfield
• If there's a snap from a field goal/punt, then there can be less than 5 players with numbers 50-79:
• All linemen not numbered 50-79 on the line are ineligible receivers. They must be on the line and not on the end of the line. All players remain ineligible throughout the down unless the ball touches an official or defensive player.

You can find last year's rule book at NCAA Publications - Playing Rules and it's a free download in pdf format as well.