The version and build number of this implementation. Version numbers for a release are of the form: w.x.y[-a]-z, where:

• w - the major version number of the release. This number should start at 1. Typically, a bump in the major version number signifies that the release breaks backwards compatibility with some older release.
• x - minor version number. This number starts at 0. A bump in the minor version number signifies a release that has significant new functionality.
• y - minor-minor version number number. This number starts at 0. A bump in the minor-minor version number signifies that new bug fixes have been added to the build.
• a - an optional build designator followed by a digit. Valid build designators are:
  • alpha
  • beta
• z - build number. This is used to specify the build number of the release. This is usually only important to people that use the daily build of a project. The format is the lower-case letter 'b' followed by a two digit number.

For example, the following are all valid version strings:

• 1.1.2-b02
• 1.3.5-alpha1-b19
• 4.7.1-beta3-b20