Ok, I feel like a noob here.

However, I'm starting to see "W" / "Premium Coach" class tickets when booking overseas travel (DFW to CDG via JFK). These seem to be associated with Air France flights.

Questions:

What advantage is "W" over "Y"?
Does this qualify for the SWU? The terms say

"For international travel, certificate may be used to upgrade only on published coach fares booked in Y, B or M class.....[snip]....Travel can be on Delta Air Lines or Delta Connection flights as well as KLM flights. .....For travel on KLM, certificate may be used to upgrade only on published fares in M, B, S or X class."

So, based on that literally, even though the W class is listed above the Y class, it does not qualify for an SWUs since it's AF metal and not KL... is that correct?

If so, that's odd as the ticket with the AF W is actually 300 less than the DL M.