Peercoin protocol versions do not represent Peercoin client versions, however client hosted at www.github.com/peercoin/peercoin is considered Peercoin reference implementation which describes the actual protocol.
Peercoin protocol version are marked using the following format:
v{major_version}.{minor_version}
where:
- v is prefix (stands for “version”)
- major_version is for capital improvements to the core concepts or complete redesigns
- minor_version is for iterative evolution of the protocol defined in the original whitepaper
Current actual protocol version is v0.6, and v0.7 is coming live at 12th of March, 2019, while current actual client is v0.7.0 which implements protocol version v0.7.
Unless there is protocol revision, minor_version variable does not get updated. For example upcoming major client upgrade (based on bitcoin-core 0.16.3) will not bump the protocol version but only a client version.