(Sarah of the Clue Crew delivers the clue from the Boudin Bakery in San Francisco, California) It once meant a notch used to record a tally in a game.  That meaning is still used for the cuts that will make your sourdough bake and look better
He reports that Austin used to be cooler (though never that cool), but, at an event 
I ... could just as easily be from Portland, Brooklyn, Toronto, or San Francisco.