The result of the play is a touchback, B 1/10 at the 25. However, B80 has committed an illegal block (6-5-4). The penalty will be enforced from the basic spot (25), so B 1/10 @15, PC 25, snap.
Bobby, if this a Basic Spot/3 & 1 enforcement foul, what is the Basic Spot for fouls that occur during the kick play portion of a down? The Previous Spot. So, if this is a BS/3&1 penalty, then, on a free kick play, it could only be enforced at the Previous Spot, and the kickoff repeated.
But, it isn’t a BS/3 & 1 penalty. In the penalty statement, it is 10-yards, enforced from the spot of the foul, with B next putting the ball in play by snap (1/10). Period. The penalty, from the B-30, would take the ball to the B-20, 1/10. Team A would accept the penalty. However, this foul could easily occur more than 10 yards ahead of the natural succeeding spot, in which case, Team A would decline.
This was once a 15-yard penalty, but, they realized it wasn’t a safety foul - just more of a procedural foul, i.e., an otherwise legal block that occurred when the block simply wasn’t permitted (just like Team A blocking early on a onside free kick). So, they reduced it to 10-yards.