I searched/still searching the forum. Find no clue. At co.com, there is a ticker for u/g using miles, and I guess it's not the same as the (old) SWU's can u/g any revenue fare. And co.com does not have the "expert" mode that let you looking at F9, C9, Y9, B9,...up to NC0, XY0,...

So how do you check the availability of the u/g space?

Thanks