In SemVer [1], it's prescribed that the first number is for breaking changes, the second number for new features, and the third number for fixes. So this would be v3.0.0.
It also allows you to add a suffix though for beta-type versions, so the beta would be v3.0.0-beta, or v3.0.0-rc1, etc.
It also allows you to add a suffix though for beta-type versions, so the beta would be v3.0.0-beta, or v3.0.0-rc1, etc.
[1] http://semver.org/