NRV (Not Really Vanished)
From Just Solve the File Format Problem
NRV (Not Really Vanished) is a data compression library, and associated demonstration software. It was developed by Markus Oberhumer, as a possible successor to LZO. It apparently had a file format associated with it.
A subset of NRV is used in UPX's UCL compression.
Despite its name, the NRV software seems to have really vanished from the internet. The website[1] indicates it was discontinued in favor of LZO Professional[2].
Identification
According to IDArc, NRV (demo) files start with bytes 00 9e 6e 72 76 ff.
Software
We haven't been able to find any NRV software. The demo software was in a file named nrvdemo1.zip.