It’s a new football formation making the rounds in the high school game. The New York Times is writing about it and there are quite a few links on Google.
By placing one of the quarterbacks at least seven yards behind the line of scrimmage, and no one under center to receive the snap, the A-11 qualifies as a scrimmage kick formation — the alignments used for punts and extra points. Thus interior linemen are granted an exception from having to wear jersey numbers 50 through 79. (The exception was intended to allow a team’s deep snapper not to have to switch to a lineman’s jersey if he was a back or an end.) Any player wearing jersey numbers 1 through 49 and 80 through 99 is potentially eligible to receive a pass.
Here is some video: