Yes this.
I just don't get it. I don't understand how it's implemented in practice.
For example if the defenders try to make a wall 11 metres away from the ball rather than 10 metres, does that mean an attacker cannot stand in front of them as he's within 1 metres of the wall?
What if it's an indirect free kick in the area, and the defenders make a line on the goal line, where are the attackers meant to stand?
Can you form two walls, and players can't be within a metre of either?
(This may well be covered in the rules but I can't be arsed looking it up properly, it's a stupid rule)