About Pxoi vs Nxoi:
We *could* make say {ni'oi} Nxoi, while xoi = Pxoi (either that or assign {pi'oi}, but I'm reluctant to use that cmavo space if we aren't gonna kill {xoi}, which might be impossible to do at this point).
On the other hand though, there might be a need for a UI to mark "non-restrictive" information, since {xoi} is proposed to be an expansion for {fi'o}, BAI, and sumtcita anyway. Thus this UI can then be useful to mark any sumtcita place (or even, say, seltau) as incidental information.
I *think* {ta'o} works for that purpose, but others might disagree. There's also {ra'unai}, but I'm not sure if it's suitable, and I'd prefer an unnegated form because I believe that information should be considered restrictive by default.