How do you identify eligible/ineligible recievers?

[Big2Cat]

However, you will also get into numbering exceptions--when teams do not have to have 5 players 50-79 in the game. This occurs in scrimmage kick formations and can cause trouble if people (and especially the U in this situation) are not paying attention.

This is also how the California coach was able to run his A-11 formation where he has all eligible numbers on the field and his formation will determine who is eligible and who is not for every down.