ICAO is currently introducing the Performance Based Navigation (PBN) concept
http://www.icao.int/pbn/ - it is supported by a draft manual which contains a number of navigation specifications for RNAV 10, RNAV 5, RNAV 2, RNAV 1, Basic RNP 1, RNP ACH and RNP AR APCH. (These nav specs provide detailed guidance on the airworthiness and operational approval requirements although they are not in themselves regulatory documents - it is up to the State to publish the requirements)
RNAV 10 = current RNP 10
RNAV 5 = B-RNAV
RNAV 2 = US RNAV Type A
RNAV 1 = US RNAV Type B and P-RNAV (as long as you can engage LNAV by 500ft agl and you don't use VOR/DME RNAV)
Basic RNP 1 = RNAV 1 for GNSS only.
RNP APCH = RNAV Approach with GNSS
RNP AR APCH = US RNP SAAAR
In Europe B-RNAV should only be used on very simple SIDs/STARs above MSA. P-RNAV is being introduced in many States
http://www.ecacnav.com/Future_Applic...nteractive_Map. P-RNAV may be based on GNSS and/or DME/DME