Ascending order. This is a very rough list - 200/300/400/500, Exage Mtn, Deore, LX, DX, XT, XTR and more. Shimano went on a model rampage at the end of the 80's/90's in the quest for world domination.
I won't bug you again about it but you paid for your membership here and it's appreciated. In return you get the privilege of requesting to buy bike parts from good, reputable people and it's free. Ebay pales in comparison. Shudder.