Knack, I don't mind at all if you print it out . That's the whole reason why I put it on here so that folks could maybe find out things that they didn't know before.
As for the extra rings on some of the bits, you'll get a different answer from everyone you ask LOL. On a curb bit, you always attach the curb strap to the ring that is above the mouthpiece. On the ones with the ring at the mouthpiece, part of the reason is that it keeps the mouthpiece stationary on the shank so that it doesn't slide up and down to create a gag action. Another part is that you can more slowly transition a horse up from a snaffle with these types of bits. You can put your reins on the rings by the mouthpiece and it makes the bit sort of a hybrid between a snaffle and a leverage bit. Along those same lines, you can use 4 reins (a pair on the mouthpiece rings and a pair on the lower rings) to help to minimize the confusion on the part of the horse and help better prepare them for the reins to be used on just the shank ends.