My instincts tell me that the #s would correspond to the letters: A=1, B=2, C=3 etc. Truth is, it doesn't matter THAT much. The 2nd run has more nutrients, but, think about it, how much *more* can it contain? If you're a purist, You can always order grade B online in gallon {or smaller} quanities, which is somewhat more cost effective... check my *syrupy sites* post in the past page or so? for links to online syrup sellers. Good luck! ~Rebeckah