@ Head

If you read section 12.2 of the Common Language Infrastructure (CLI) Partition II document, you'll see the following part in regards to interface implementation:

If there are any virtual methods in the interface that still have empty slots, see if there are any public virtual methods, but not public virtual newslot methods, available on this class (directly or inherited) having the same name and signature, then use these to implement the corresponding methods on the interface.

The key thing to note here is the "or inherited" part.  This means for example, you may have a something like ToXML member of an interface, which is well suited into factoring into a base class .  The CLI allows for this by requiring the member match by name and signature.

This is where the interface is implied.  This important aspect is being left out of the proposed re-appropriating of VB's existing explicit interface syntax.