I was checking on how full F was on a couple of flights next Thursday and I was surprised to see X inventory being reported on EF. Both flights showed F8 but it was interesting to see that both flights also reported X2. I guess that means that US RM has pre-allocated 2 F seats for upgrade at T-100.

I also checked a couple of days of PHL-ORD to see if EF would show AA X inventory via US codeshare. It seems to do so although most show X0 but some showed positive inventory. On one US flight, they showed X6. This was all > 100 hours out.