I found some of the RNAV, RNP and the now all in together PBN information a bit difficult to comprehend, so I took a bunch of notes from various internet sources and combined it into my own notes for reference.
For RNP-10 this is part of my information. Let me know if there are any errors.
"Required Navigation Performance (RNP) standards are almost always performance based, requiring on-board performance monitoring and alerting. This is as opposed to the older RNAV systems which are an equipment-based standard that do not require on-board performance monitoring and alerting.
We say almost always because RNP-10 is an exception. Many areas of the world adopted "RNP-10" as synonymous with "RNAV-10," violating the method ICAO set up in ICAO Doc 9613 - Performance Based Navigation.
ICAO decided (due to some lobbying) not to re-name RNP10 and therefore to retain the "RNP-10"name when in fact it meant "RNAV-10". This was because changing all the charts and manuals would have been very expensive.
The key takeaway from all this is to realize that "RNP-10" does not require performance monitoring and alerting, as do the other RNP designations."
Because of the underlined statement, I have always wondered if that is the reason our FMC stays at RNP/ANP 12.0/XXX instead of automatically switching to 10.0/XXX with the x's being actual numbers of error. We have to manually select an RNP of 10 when in RNP 10 airspace(for the few pilots that actually do it) while the RNP value in the FMC automatically switches to the correct value for other enroute airspace.