I never had a criteria written down for Black Belt.. And when it came time for a student to make black, it was the only rank that didn't have a test involved, I just promoted them. And always on a night when the gym was packed, and usually with guests and/or with one of my many instructors.
There was a certain attitude about a criteria, though. Posted on one of the walls was info about "green belt", which I considered half way to black. (it went green, brown, black) It said,
"A green belt has to know how to fight. Doesn't necessarily have to be good at it yet, but must be prepared and able to do it every single night. You can hit a green belt with a stick, a green belt does not care."
Posted below those words was a nifty photo I had of a military K-9 in full, flying assault of a guy in full bite suit, who is whipping the crap out of the dog with a stick - while the dog is just tearing him a new one.
I know that might sound silly, macho, whatever, but it was part of what we considered our Martial attitude. Fighting and fitness was the second biggest part of what we always did. (You specifically got fit for fighting, not health) (I know, my bad) Being a lady or a gentleman was the first. As for black belt, beside knowing the system inside and out, you had to be able to fight like a son of a *****. Anyone, anywhere, under any circumstances, in any kind of fighting. Even if it was fighting you weren't familiar with, you just did it, got your butt kicked, and politely and sincerely asked those who kicked your butt for some instruction. (We got our butts whooped many times)
I'm not saying that's right, wrong or any better or worse than anything else. It's just what we did.
And it sure is fun.