I have done a bit of research and am still confused.

When Expert Flyer shows R availability, I bring that info to the Delta DM desk, they say, "Oh, we only have RD & RK availability for that flight, you need R." It appears as though EF lumps the low (R) and middle (RD) together, but I can't confirm that.

Adding to my confusion, an email from EF says: "We only show DL economy low level award availability (N class) not Business or First inventory." Yet I see R and O in the results of their searches.

If anyone can shed light on any of this, it would be greatly appreciated.

Thanks.