What is this blue book? I'm an Aikikai nidan and I've never seen nor heard about blue books. I have a card with my rankings, and I had some kind of membership card I think. Neither is blue.
when you buy "used" car in the U.S., you go and check the blue book value which shown the estimated worth of the car. same in this case, the blue book is to show you your aikido value over time, which will be less and less over the year, as older car worth less; unless it's a good reliable model or one of those old restored car, then it worth more.