Secondly, you have the list in the wrong order — e.g. U should go higher up, S and G at the end. It needs to be in descending order of price. And why don't you include T and L if you're going to have S and G?
List order has no effect on the results on United.com. It searches for the lowest available within all of the fare codes you enter. You can enter "Y,B,M,E,H" or "H,E,M,B,Y" and an "H" fare will always show up (assuming one is available).
-RM