NetVault Backup 10 has introduced a new 4-number versioning convention.
For instance, at the time of this article, the current version is 10.0.1.24 where:
10 <version major>
0 <version minor>
1 <maintenance level>
24 <patch>
The same system will now apply to newly built Plug-ins as well as SmartDisk and NVBMR.
The new plug-ins will also use the 4-number versioning, but until that time, you can still download database plug-ins bearing a 3-number version convention.
For example, the current Plug-in for Exchange is 5.1.1
5<version major>
1<version minor>
1<patch>