Numbers on BR-9000 brakes?
Not an earth-shattering question, but I just noticed on the inside bottom of the brake pad holders near the "wing" and the wear-indicator screw, there is a number. On my Dura-Ace 9000 brakes, three of the four holders are marked with a "3" and one is marked with a "2". All four holders look and measure identical.
I thought I understood the Shimano date code strategy (and I see the codes on the body of the brakes), but what are these numbers and why is one different?