substitution vs participation

[daggo66]

Originally Posted by hawkishowl20

Youngump asks a great question and the answer is simple you can stop play after it starts and call the dead ball foul.

*3.7 COMMENT, Page 26: a. If a replaced player or substitute attempts to leave the field, but does not get off prior to the snap, the foul is considered as having occurred simultaneously with the snap and the illegal substitution penalty is enforced from the previous spot. (3-7-4, 10-4-2a)

Since when can we stop play after it starts? Please do not quote from outdated books. Get yourself a 2008 rulebook and casebook and start reading for comprehension.