Great recap of the history. The substitution rules were expanded from each player being within 15-yards of the ball to the modern field usage of being "inside the numbers" of nine yard-marks. These are the yardage numerals you see on most fields today 5, 10, 15, 20 etc... which are nine yards from each sideline. All players must be within the numbers between the ready for play and the snap. If not then they are substitutes (not players) and there is a foul for illegal substitution which combats the "sleeper" sideline huggers from trying something devious.
Great recap of the history. The substitution rules were expanded from each player being within 15-yards of the ball to the modern field usage of being "inside the numbers" of nine yard-marks. These are the yardage numerals you see on most fields today 5, 10, 15, 20 etc... which are nine yards from each sideline. All players must be within the numbers between the ready for play and the snap. If not then they are substitutes (not players) and there is a foul for illegal substitution which combats the "sleeper" sideline huggers from trying something devious.
Thanks for the update. Football is all about the numbers.
#5 "TD of field goal" should be "or field goal", and should include a two-point conversion.