Binary Compatibility Changes in Visual Basic
Visual Basic .NET updates the mechanism for preserving compatibility with older versions of a component.
Visual Basic 6.0
In Visual Basic 6.0, the Binary Compatibility option allows you to automatically retain class and interface identifiers from a previous version of a component when you compile a new version. The new version contains both the old identifiers and the new identifiers, and client applications can continue using the old interface to your component without having to be updated.
Visual Basic .NET
In Visual Basic .NET, binary compatibility is accomplished using attributes. This gives you direct control over the information placed in your compiled component, such as class and interface identifiers, virtual table offsets, and any appropriate COM attributes. Because you can explicitly select attributes for preservation, the Binary Compatibility option is not supported.