Jas 3 versions follow 3.A.B format, where A and B correspond to major and minor version numbers.
The major version number is incremented when some essential new functionality is added, or when Jas 3 behavior is changed in a significant and possibly incompatible way. Minor version numbers usually designate maintenance releases - bug fixes and minor improvements.
Built-in plugins are a part of the Jas 3 core distribution and have the same version number. Extensions and user-written plugins follow their own versioning schemes.
Before the 3.0.0 release, Jas 3 beta releases followed 0.A.B format.