This pages describes the version schema that I use for my Typo3 extension. It guarantees a consistent on view on the contents of new versions and especially makes it clearer to you, what to expect in terms of possibly required migration efforts.
<release>.<major_version>.<minor_version>
Release <release>
A release is a new version that incorporates many heavyweight changes of any type: addition of new features, deletion of obsolete code or even a completely new extension architecture. So do not expect to update a previous version to a new release without migration of the extension’s data. And read the corresponding release very carefully before upgrading!
Example: CWT Community 1.1.0 ==> CWT Community 2.0.0
Major Version <major_version>
A new major version typically contains new functions, enhancements and improvements to an existing extension. Moreover it is likely that an update to a new major version raises the need of changes to “old” resources (such as HTML templates, Typoscript configuration, etc. provided by the previous version). So you are encouraged to read the according release notes carefully.
Example: CWT Community 1.1.0 ==> CWT Community 1.2.0
Minor Version <minor_version>
A minor version only contains bugfixes (such as security fixes) to an existing major version of an extension. Thereby it is guaranteed that you may update an older minor version with no changes at all.
Example: CWT Community 1.1.0 ==> CWT Community 1.1.1