What is the standard for system versions management (release management)?

This is the usual method of software versioning.  X.Y.Z corresponds to major.minor.patch:

• Major version numbers change whenever there is something significant, a large or potentially backward-incompatible change to the S/W package
• Mino version numbers change when a new, minor feature is introduces, or when a set of smaller features roll out
• Patch numbers change when a new build of the S/W is released. This is normally for small bugfixes.