The UA classes in this thread for upgrades are slightly misleading and need clarification.
The R O and N classes listed are used *only* for M+ members that are logged on and looking for reward space on the UA www site.
They are purely a UA "in-house" www class bucket only, used for UA's saver awards.
If looking on a CRS or via other carriers, you still need to look/book O I and X (Star Standard) classes for UA rewards.

Cheers.