Can someone go to this page and answer a couple questions on the grading of this note? The page is: http://coins.heritagegalleries.com/common/view_item.php?Sale_No=36021&Lot_No=22237 First, what's the significance of the "block" designation (in this example, D-A). Second, I guess I'd want a good online reference to help me figure out these things, namely, such as the 66PPQ grade designation in the example. I have notes, but I have no idea as to the various grades, the significance of the serial and other numbers, and how they're graded. Is there a good online reference I'd want to check out? Thanks.
