Which is why it's ambiguous. I'm fully aware that it's possible CB intended for them to be centred, but they simply said 'at' rather than 'centred on'. Words matter and 'at' does not mean 'centred on'. If CB wants it to say 'cented on' that's an extremely easy errata. Or, you know, you can make an argument from authority and I'll shut up. But while you keep going with 'I think' rather than 'this is the way it's played' then it remains a point for debate.
The argument from authority fallacy is only an issue when you aren't dealing with a fiat system. If someone has the power to make something true simply by saying it, it's not a fallacy. Just unwise to abuse [emoji14] My point being that if you go "this is what the rules were meant to say" I'll shut up and go "because IJW said so" when people ask me why it's played that way. I'll then patiently wait for an FAQ to make it clear in a way that doesn't require searching through the forums to demonstrate.