In Oz, we have RNP2 standards - no idea if that is the same as RNAV2. I work Radar Approach so never use them, but there are standards for 30NM, 20NM and 15NM in MATS with a variety of conditions.
e.g. 15NM separation - one aircraft maintains a level while the other changes level.
a) Distance information is provided by:
i) DME; or
ii) GNSS in CTA only, by GPSOCEANIC, RNP2 or RNP4 approved aircraft;
b) One aircraft maintains level while vertical separation does not exist and;
c) Above FL290, when a DME distance is provided, both aircraft must be on the same side of the DME beacon.