Very nice, this will help alot of people out, btw, I think that High is the highest you can sell it and Low is the lowest you can buy it.
I think I know, what fill means:
When you are buying more than one item at once say 10 for example it shows how many of those orders were fulfilled. If one transaction was done succesfully fill goes to 1. If you bought 3 of the ordered 10 it goes to 3 etc.