Visual Basic for Applications Reference
Specifies an interface or class that will be implemented in the class module in which it appears.
Implements [InterfaceName | Class]
An interface is a collection of prototypes representing the members (methods and properties) the interface encapsulates; that is, it contains only the declarations for the member procedures. A class provides an implementation of all of the methods and properties of one or more interfaces. Classes provide the code used when each function is called by a controller of the class. All classes implement at least one interface, which is considered the default interface of the class. In Visual Basic, any member that isn't explicitly a member of an implemented interface is implicitly a member of the default interface.
When a Visual Basic class implements an interface, the Visual Basic class provides its own versions of all the Public procedures specified in the type library of the Interface. In addition to providing a mapping between the interface prototypes and your procedures, the Implements statement causes the class to accept COM QueryInterface calls for the specified interface ID.
Note Visual Basic does not implement derived classes or interfaces.
When you implement an interface or class, you must include all the Public procedures involved. A missing member in an implementation of an interface or class causes an error. If you don't place code in one of the procedures in a class you are implementing, you can raise the appropriate error (Const E_NOTIMPL = &H80004001) so a user of the implementation understands that a member is not implemented.
The Implements statement can't appear in a standard module.