When a test case is created, it has a version number of 1. When a new version is derived, the version number is incremented by 1. The Draft and Final statuses actually apply to this first version.
To modify a test case after it is in Final status, a new version of that test case must be derived. A new version can be derived from the latest version of a test case only when the latest version has the Final status.
Each test case has one version that is designated as the "current" version. The "current" version of a test case is automatically picked as the version to use when including in test suites or test sessions, for example. The "current" version of a test case is typically the most recent version but it can be an earlier version also.
When a test case is created, the first version is created. Until the version is marked as having Final status, it has a status of Draft. When its status is set to Final, this first version automatically gets designated as the "current" version. When a test case has evolved with multiple versions, any version that has a status of Final can be designated as the "current" version.
The test case feature is available to users with test coverage permissions for the project. Project owners can manage the permissions of project members.