>>42488235
That's cute worldbuilding, but in reality it's an extremely stylized way of showing a curved brim. I'm always amused by the number of fans that translate it literally into a notch. Even the nu-writers gave Mean AJ a variant of notch, which doesn't help.
>>42487741 (OP)
Speaking of, are you going to curve the sides? You could do more under the brim if they're high enough.