Version Numbering Changes in Visual Basic .NET
In Visual Basic 6.0, setting the Major, Minor, and Revision properties of the App object controlled the version number for an application. For example, setting Major to 1, Minor to 2, and Revision to 3 resulted in a version number of 126.96.36.199.
In Visual Basic .NET, the version number properties are replaced by the AssemblyVersion attribute, which has four parts: Major, Minor, Revision, and Build. For the above example, the resulting version number would be 1.2.3.x, where x is a build number that is incremented each time the assembly is built.
When an application is upgraded from Visual Basic 6.0, only the Major and Minor properties are upgraded; Visual Basic .NET assigns new values for the Revision and Build properties.